JP2012138851A - Image transmission device and method, and image receiving device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image transmission device and method and an image receiving device and method enabling transmission of a higher-quality image while reducing transmission delay.SOLUTION: A compression part reversibly compresses an input image to obtain compressed data of the image. A transmission part sequentially transmits the compressed data from a high-order bit side, as plural divided pieces of data packets. A determination part determines whether the display of the image on a receiving side stops for a fixed period or longer. If the determination part determines that the display of the image on the receiving side stops for the fixed period or longer, the transmission part continues transmission of the compressed data being transmitted.

Description

  Embodiments described herein relate generally to an image transmission apparatus and method, and an image reception apparatus and method.

  There is an image transmission apparatus that transmits high-quality images with reduced transmission delay by using an encoding method that improves image quality when additional data such as hierarchical encoding, JPEG2000, or progressive JPEG is received. For example, when sequentially transmitting compressed data of frames input in time series, even if a frame currently being transmitted is still being transmitted at the timing at which the next frame should be transmitted, If the image quality is satisfied, the transmission is stopped and transmission of the next frame is started. If the predetermined image quality is not satisfied, the transmission is continued.

  In such an image transmission apparatus, an apparatus capable of transmitting a higher quality image while reducing transmission delay is desired.

JP 2009-159288 A

  The problem to be solved by the invention is to provide an image transmitting apparatus and method, and an image receiving apparatus and method capable of transmitting a higher quality image while reducing transmission delay.

  In order to solve the above-described problem, an image transmission apparatus according to an embodiment of the present invention is an image transmission apparatus that transmits a compressed moving image to a reception side, and includes a compression unit, a determination unit, a transmission unit, Is provided.

The compression unit reversibly compresses the input image to obtain compressed data of the image. The transmission unit sequentially transmits the compressed data as a data packet divided into a plurality from the upper bit side. The determination unit determines whether or not the display of the image is stopped for a predetermined time or more on the receiving side. When the determination unit determines that the display of the image is stopped for a predetermined time or longer on the reception side, the transmission unit continues to transmit the compressed data being transmitted.

  An image receiving apparatus according to another embodiment of the present invention is an image receiving apparatus that receives a moving image from the transmitting side, and includes a receiving unit, an expanding unit, and a command transmitting unit.

  The receiving unit sequentially receives a part of the compressed data of each frame of the moving image from the top. Whether the expansion unit expands a part of one frame of compressed data received at an arbitrary timing based on a playback mode indicating whether or not the progressive mode is received, or expands after receiving all the compressed data And decompress the received compressed data. The command transmission unit transmits a reproduction command indicating whether the reproduction state or the pause state to the transmission side. When the transmission command transmission unit transmits the playback command in a paused state, the reception unit continues to receive the compressed data until all the compressed data being received is received, and the decompression unit receives The decompression of the compressed data is continued.

1 is a block diagram illustrating an image transmission device 1 according to a first embodiment. FIG. 4 is an exemplary diagram illustrating a structure of a data buffer 121. Explanatory drawing of the compression data packet 102. FIG. 6 is a flowchart showing processing of the compression unit 11. 5 is a flowchart showing processing of a data transmission unit 122. The block diagram showing the image transmitter 2 which concerns on 2nd Embodiment. The flowchart showing the process of the determination part 24 and the compression part 11. FIG. The block diagram showing the image receiver 3 which concerns on 3rd Embodiment. 5 is a flowchart showing processing of the receiving unit 30. 7 is a flowchart showing processing of the decompression unit 32. Explanatory drawing of the effect of the system using the image transmitter 1 and the image receiver 3. FIG. Explanatory drawing of the effect of the system using the image transmitter 2 and the image receiver 3. FIG.

(First embodiment)
The image transmission device 1 according to the first embodiment transmits data that has been irreversibly compressed from a moving image to a reception-side device (image reception device). The image transmission device 1 can be used in, for example, a thin client system.

  The image transmission device 1 receives each frame of a moving image as an input image and performs, for example, lossless compression. Lossless compression data is generated by truncating the lower bit side of the lossless compressed data at an arbitrary position. Such a compression method capable of generating lossy compression data is hereinafter referred to as a specific compression method. The image transmitting apparatus 1 transmits the compressed data obtained by the specific compression method to the receiving side in an arbitrary data size in order from the higher bit side.

  When the moving image is in a playback state in the image receiving apparatus, the image transmitting apparatus 1 sequentially transmits compressed data having a data size corresponding to the frame rate to the receiving side. When the moving image is temporarily stopped in the image receiving device, the transmission of the compressed data of the image when the image transmitting device 1 is temporarily stopped is continued.

  Thereby, the image transmission device 1 can transmit a higher quality image while reducing transmission delay.

  FIG. 1 is a block diagram illustrating the image transmission device 1. The image transmission device 1 includes an input unit 10, a compression unit 11, a transmission unit 12, a command reception unit 13, and a determination unit 14. The transmission unit 12 includes a data buffer 121 and a data transmission unit 122.

  The input unit 10 inputs an input image 100 to be compressed.

  The compression unit 11 compresses the input images 100 sequentially input as moving images using a specific compression method. Examples of the specific compression method include JPEG2000.

  The data buffer 121 stores a stream of compressed data (compressed data stream 50) of a plurality of frames ((N + 1) frames). The compressed data stream 50 includes compressed data 101.

  The data buffer 121 has a structure as shown in FIG. 2, for example, and may be capable of storing a compressed data stream 50 of (N + 1) frames. When the image transmission apparatus 1 is activated, the data buffer 121 prepares a buffer for the (N + 1) compressed data stream 50. The compression unit 11 initializes a register (not shown) that holds “stored_Idx” indicating an index for storing the compressed data stream 50. The compression unit 11 initializes a register (not shown) that holds “stored_Num” indicating the number of compressed data streams 50 currently stored. FIG. 2 shows an example of stored_Idx = 3 and stored_Num = 3.

  The data transmission unit 122 packetizes a part of the compressed data stream 50 stored in the data buffer 121 into a compressed data packet 102 and transmits it to the receiving side. In this embodiment, TCP / IP is used as the transmission protocol, but transmission may be performed using another transmission protocol. The compressed data packet 102 will be described later.

  The command receiving unit 13 receives a request (transmission request) from the receiving side and a command 103 indicating a device operation on the receiving side. Examples of the command 103 include a session start command, a session end command, a transmission mode, a frame rate of a moving image to be received, image quality, a playback command (pause / playback start), and the like.

  Here, the transmission mode includes two modes, a “lossless mode” in which all compressed data is transmitted and a “lossy mode” in which irreversible compressed data in which the lower bits of the compressed data are truncated is transmitted. The receiving side may be able to switch between the lossless mode and the lossy mode by inputting the transmission mode as the command 103 at an arbitrary timing.

  When the lossy mode is designated as the transmission mode, the receiving side may further transmit information indicating the transmission image quality using the command 103. The information indicating the transmission image quality is, for example, information such as how many bits from the MSB side are not discarded when the compressed data is compressed by a bit plane, or a PSNR (Peak Signal to Noise Ratio) with the input image 100. Any information may be used as long as the information indicates the image quality of the image to be transmitted.

  The playback command is a command for instructing to start or pause playback of an image received on the receiving side. The state of the image transmission device 1 is in an initial state (INIT) when activated, and when the command receiving unit 13 receives a command for starting a session (session start command), initialization necessary for compression is performed. After performing, it will be in a reproduction waiting state (READY).

  When the command reception unit 13 receives the reproduction start command, the compression unit 11 starts input of the input image 100, and the image transmission device 1 enters the reproduction state (PLAY). When the command reception unit 13 receives the pause command, the compression unit 11 pauses the input of the input image 100, and the image transmission apparatus 1 enters a pause state (PAUSE).

  When the command receiving unit 13 receives a command for ending the session (session end command), the compression unit 11 stops the compression. The data transmission unit 122 stops transmission and discards data remaining in the data buffer 121. Then, the state of the image transmission device 1 returns to the initial state (INIT) again.

  The determination unit 14 determines whether or not the moving image displayed on the receiving side is stopped for a predetermined time or more. In the present embodiment, the determination unit 14 determines whether or not the data transmission unit 122 continues to transmit the compressed data packet 102 of the image currently being transmitted based on the reproduction command.

  When the determination by the determination unit 14 is NO (false) (that is, in the reproduction state), the data transmission unit 122 sequentially reads a part of the compressed data stream 50 stored in the data buffer 121 from the head, and compresses the compressed data. Transmit as packet 102. When the determination by the determination unit 14 is YES (true) (that is, in the case of temporary stop), the data transmission unit 122 continues transmission of each compressed data packet 102 of the image being transmitted. The input unit 10, the compression unit 11, the transmission unit 12, the command reception unit 13, and the determination unit 14 may be realized by a central processing unit (CPU) and a memory used by the CPU. A graphics processing unit (GPU) may also be used.

  The configuration of the image transmission device 1 has been described above.

  Here, the compressed data packet 102 will be described. FIG. 3 is an explanatory diagram of the compressed data packet 102. In the compressed data stream 50, time_stamp for identifying the compressed data 101 and min_size indicating the data size of the base layer are added to the head of the compressed data 101. Here, the basic layer is data including, for example, data that is necessary for decompressing compressed data, among compressed data, and is data that cannot be decompressed when truncation is impossible.

  The compressed data packet 102 is obtained by packetizing the compressed data stream 50 with an arbitrary data size. A packet header is added to the head of the compressed data packet 102.

  The packet header includes a packet size indicating the size of the compressed data packet 102, frame head information indicating whether or not the added compressed data packet 102 is the head of the frame, and the added compressed data packet 102 is the end of the frame. Frame end information indicating whether or not.

  The frame end information includes an end flag (end_flag) that is a flag indicating whether the added compressed data packet 102 is the end of the frame (TRUE) or not (FALSE), and whether the compressed data packet includes the end of the compressed data. Including a lossless flag.

  The compressed data packet 102 has been described above.

  FIG. 4 is a flowchart showing the processing of the compression unit 11.

  The flowchart of FIG. 4 starts from a state in which the input unit 10 inputs the input image 100 to be compressed and supplies the input image 100 to the compression unit 11. Note that the input image 100 is designated from the receiving side or input at a preset frame rate.

  The compression unit 11 determines whether or not the data buffer 121 is empty (S301). This can be determined by whether the value of stored_Num is smaller than N or not. That is, when stored_Num> N, it may be determined that the data buffer 121 is not empty, and when stored_Num ≦ N, it may be determined that the data buffer 121 is empty.

  When the determination in step S301 is NO, the compression unit 11 discards the input image 100 (S302) and ends the process.

  When the determination in step S301 is YES, the compression unit 11 compresses the input image 100 using a specific compression method, and generates compressed data 101 (S303). The compression unit 11 stores the compressed data 101 in the stored_Idxth of the data buffer 121 (S304). In FIG. 3, the stored_Idx-th buffer address is denoted as buf [stored_Idx]. The compression unit 11 updates stored_Idx (S305) and ends the process. For example, when stored_Idx <N, the compression unit 11 adds 1 to stored_Idx, and when stored_Idx is N, stored_Idx is set to 0. Then, the stored_Num value is incremented by one.

  The processing of the compression unit 11 has been described.

  FIG. 5 is a flowchart showing processing of the data transmission unit 122. The data transmission unit 122 starts processing when the image transmission device 1 is activated and the command reception unit 13 receives a session start command from the reception side.

  The data transmission unit 122 initializes “bufptr” indicating the head address of the compressed data packet 102 to be transmitted next on the compressed data stream 50 in the data buffer 121. “Data_Idx” indicating that the compressed data packet 102 is transmitted from the compressed data stream 50 stored in the index of the data buffer 121 is initialized. “End_flag” indicating whether or not to stop transmission of one frame of compressed data is initialized (S401). For example, the data transmission unit 122 may be initialized as bufptr = 0, data_Idx = 0, and end_flag = FALSE.

  The data transmission unit 122 determines whether the session has ended (S402). If the determination in step S402 is yes, the data transmission unit 122 ends the process.

  When the determination in step S402 is NO, the data transmission unit 122 determines whether there is compressed data in the data buffer 121 (S403). For example, it may be determined whether there is compressed data in the data buffer 121. In that case, the determination may be made based on whether stored_Num> 0, for example.

  If the determination in step S403 is NO (stored_Num = 0), the data transmission unit 122 waits for a predetermined time, and then transitions to step S402.

  When the determination in step S403 is YES (stored_Num> 0), the data transmission unit 122 determines whether or not the state of the image transmission device 1 is the playback state (PLAY) (S405).

  When the determination in step S405 is YES (playback state), the data transmission unit 122 determines whether the previously transmitted compressed data packet 102 is the end of the frame (S406). This may be determined by whether or not end_flag is TRUE.

When the determination in step S406 is NO (end_flag = FALSE), the data transmission unit 122 determines whether the transmission mode is the lossless mode or the lossy mode (S409).

  If the determination in step S406 is YES (end_flag = TRUE), the data transmission unit 122 sets end_flag to FALSE (step 407), and transitions to step S409.

  If the determination in step S405 is NO (not in the playback state), it is determined whether or not the compressed data packet 102 transmitted last time is not the end of the frame (end_flag is FALSE) (S408). . If the determination in step S <b> 408 is NO (not in the pause state or in the pause state and end_flag is TRUE), the data transmission unit 122 waits for a certain time (S <b> 404) and transitions to step 402.

  If the determination in step S409 is the lossy mode, the data transmission unit 122 determines whether to stop transmission of the frame being transmitted (S410). In this determination, when the playback state is set, for example, when stored_Num> 1, end_flag may be set to TRUE as an abort.

  Whether the transmission bandwidth is monitored and the transmission of the amount of data that can be transmitted at the frame interval calculated based on the designated frame rate is completed with the payload size (payload_size) of the compressed data packet 102 to be generated next When the transmission is completed, it may be determined that the transmission is terminated. Here, the payload size indicates the size of the data body excluding the packet header from the compressed data packet 102.

  At this time, it may be determined that transmission is not interrupted until the image quality becomes the same as that of the previous frame so that the transmission image quality is as constant as possible. Also, when image quality is specified in the lossy mode, it is determined whether or not the transmission of the data size that achieves the image quality with the payload size of the compressed data packet 102 to be generated next is completed. End_flag may be set to TRUE as censoring.

  When the determination in step S410 is YES (stops transmission), the data transmission unit 122 sets end_flag to TRUE (S411), and determines whether or not the compressed data packet 102 to be transmitted is the end of the compressed data stream 50 of the frame. Determination is made (S412). Whether or not it is the end is determined by adding the payload size (payload_size) of the packet to bufptr indicating the head position of the compressed data packet 102 to be transmitted next to the frame being transmitted from the size (stream_size) of the entire compressed data stream 50 You may judge by whether it is large.

  Further, as long as the transmission is aborted so that the frame rate can be maintained, the determination may be made by a method other than the method described here. In the case of the temporary stop state, it is determined that the transmission is not aborted.

  When the determination in step S410 is NO (transmission is not aborted), the process proceeds to step S412. When the determination in step S409 is the lossless mode, the process proceeds to step S412.

If the determination in step S412 is YES (termination), the data transmission unit 122 sets end_flag to TRUE (S413). Note that the payload size may be a predetermined value (1024 bytes or the like), or may be calculated and used for each compressed data packet 102 so that it can be sufficiently sent at intervals of one frame below the transmission band. . For example, when the transmission band is bandwidth (bps) and the frame rate is framerate (fps), payload_size (byte) may be calculated by Equation 1, for example.

Here, the number “8” on the right side is a value for converting byte units into bit units. When end_flag is set to TRUE in step S413, the payload size may be changed to a value calculated by Equation 2, for example.

  The data transmission unit 122 generates the compressed data packet 102 (S414). As shown in FIG. 3, for example, the compressed data stream 50 is stored in the data buffer 121 with a 4-byte time stamp and a 4-byte minimum size (min_size) added to the compressed data 101, for example.

  Here, min_size is a value indicating the size of data that cannot be discarded among the compressed data 101. bufptr indicates an address on the compressed data 101 to which time_stamp and min_size are assigned, and initially indicates 0, that is, the head.

  In step S414, the data transmission unit 122 cuts out data by the data size indicated by payload_size from the address indicated by bufptr, and, for example, 4 bytes of packet size, 1 byte of frame head information, and 1 byte of frame end information are recorded at the head of the data. The compressed data packet 102 is added.

  The packet size may be the number of bytes of data including all of the packet size, frame head information, frame end information, and extracted compressed data, or may be the number of bytes of the extracted compressed data 101.

  For example, the frame head information is 1 when bufptr is 0, and is 0 when bufptr is non-zero. The frame end information is set to 0 when end_flag is 0, for example. If end_flag is 1 and the end of the compressed data is not included in the extracted compressed data, that is, it is 1 if it is impossible to transmit reversible compressed data even if the packet is transmitted. If end_flag is 1 and the end of the compressed data is included in the extracted compressed data, that is, 2 if reversible data can be transmitted by transmitting the packet.

  The data transmission unit 122 transmits the generated compressed data packet 102 to the reception side (S415). When the transmission ends, the data transmission unit 122 discards the compressed data 101 stored in buf [stored_Idx] and sets bufptr = 0 if end_flag is TRUE. Further, if stored_Idx is N, the data transmission unit 122 sets stored_Idx = 0, and if it is smaller than N, the data transmission unit 122 increments stored_Idx by 1 and decrements stored_Num. On the other hand, if end_flag is FALSE, bufptr is incremented by the payload size (S416). Thereafter, the process proceeds to step 402.

  The processing of the data transmission unit 122 has been described.

  The present embodiment has been described above.

  For example, when the conventional technology is used for image transmission in a remote image diagnosis system, when a diagnostician (reception side) performs diagnosis by moving images, it is sufficient when there is a large amount of data that satisfies a predetermined image quality with respect to the transmission band. Cannot be played back at different frame rates.

  Further, according to the related art, when a still image is input or a diagnostician (reception side) issues a pause instruction, a lossless image cannot be displayed when it is desired to evaluate an image of a certain frame in more detail.

  In this embodiment, when the receiving side selects the lossless mode, the input image can be transmitted without loss, and when the lossy mode is selected, transmission can be performed while maintaining the frame rate by the transmission abortion process.

  Further, when a pause is instructed, it is possible to transmit a higher quality image by continuing the transmission without stopping the transmission of the compressed data of the frame. That is, when the paused state continues for a certain time or longer, a lossless image can be transmitted.

(Second Embodiment)
The image transmission apparatus 2 according to the second embodiment is configured to input an input image when two or more input images 100 that are continuously input are substantially the same (that is, when a still image is input). The main difference from the image transmitting apparatus 1 is that the transmission of 100 compressed data 101 is continued.

  FIG. 6 is a block diagram showing the image transmission device 2. The image transmission device 2 includes a determination unit 24, an image buffer 25, a compression unit 11, and a transmission unit 12. In FIG. 6, the image transmission device 2 includes the command reception unit 13 in the image transmission device 1, but may not include the command reception unit 13.

  The image buffer 25 stores a past image 200 of a frame at a time earlier than the input image 100 (for example, the immediately preceding frame).

  The determination unit 24 determines whether or not the moving image displayed on the receiving side is stopped for a predetermined time or more. In the present embodiment, the determination unit 24 compares the past image 200 stored in the image buffer 25 with the input image 100 to determine whether the input image 100 is substantially the same as the past image 200 ( That is, it is determined whether or not the image is a still image. The determination unit 24 notifies the compression unit 11 of the determination result.

  The configuration of the image transmission device 2 (mainly different from the image transmission device 1) has been described above.

  FIG. 7 is a flowchart showing processing of the determination unit 24 and the compression unit 11. In the flowchart of FIG. 7, step S701 and step S702 are added to the flowchart of FIG.

  Step S701 will be described. In step S301, when the compression unit 11 determines that the data buffer 121 is free, the determination unit 24 compares the input image 100 with the past image 200 stored in the image buffer 25, and the input image 100. Is substantially the same as the past image 200 (that is, whether or not it is a still image) (S701). If the determination in step S701 is YES (still image), the process proceeds to step S302. If the determination in step S701 is NO (not a still image), the process proceeds to step S303.

  Step S702 will be described. When the process of step S305 ends, the compression unit 11 stores the input image 100 in the image buffer 25 (S702). The stored input image 100 becomes the past image 200.

  The processes of the determination unit 24 and the compression unit 11 have been described.

  The processing of the data transmission unit 122 is the same as the flowchart shown in FIG. However, the difference is that the transmission is not terminated when it is determined in the process in step S410 that the frame input next to the frame being transmitted is a still image.

  As described above, according to the present embodiment, when a still image is input, it is more reversible by continuing to transmit the compressed data 101 of the frame being transmitted to the end until the next different image is input. It is possible to transmit compressed data close to. Furthermore, if the time of the still image continues, a reversible image can be finally transmitted.

(Third embodiment)
The image receiving device 3 according to the third embodiment receives the compressed data packet 102 from the image transmitting device 1 or the image transmitting device 2 on the transmission side, and generates an image obtained by expanding the compressed data packet 102. Is.

  FIG. 8 is a block diagram showing the image receiving device 3. The image reception device 3 includes a reception unit 30, a data buffer 31, an expansion unit 32, and a command transmission unit 33. The image reception device 3 may be connected to the image transmission device 1 or the image transmission device 2 via a network such as the Internet, an intranet, or a wireless LAN.

  The receiving unit 30 receives the compressed data packet 102 from the transmission side and extracts the compressed data 101. The data buffer 31 stores the compressed data 101. The decompressing unit 32 reads the compressed data 101 from the data buffer 31 and generates a decompressed image 300. The command transmission unit 33 transmits a transmission request to the transmission side. The transmission request includes the transmission mode, the frame rate of the moving image to be transmitted, the image quality of the moving image, and the playback command.

  The command transmission unit 33 transmits a transmission request related to transmission to the image transmission apparatus among commands 104 specified from a UI (not shown) used by the user on the reception side. Note that the command 104 further includes a command for designating a playback mode. The playback mode includes a full frame mode and a progressive mode.

  When the full frame mode is selected by the user on the receiving side, the decompressing unit 32 decompresses the compressed data 101 after receiving all the compressed data 101 of one frame. When the progressive mode is selected, the decompressing unit 32 decompresses a part of the received compressed data 101 of one frame. Whether or not all the compressed data of one frame has been received may be determined from the frame end information of the packet header shown in FIG.

  The configuration of the image transmission / reception device 3 has been described above.

  The state of the image receiving device 3 is in an initial state (INIT) at the time of activation, and when the command transmission unit 33 transmits a session start command, initialization necessary for decompression is performed, and then a reproduction waiting state (READY) is set. Become.

  When the command transmission unit 33 transmits the reproduction start command, the reception unit 30 starts reception of the compressed data packet 102, and the image reception device 3 enters a reproduction state (PLAY). The extracted compressed data 101 is stored in the data buffer 31. Similar to the data buffer 121 described above, the data buffer 31 has the structure shown in FIG. 2, for example, stored_Idx = 0 and stored_Num = 0 at initialization, an index for storing the compressed data 101, and stored compression Initialize the number of frames of data.

  When the command transmission unit 33 transmits a pause command, the state of the image reception device 3 becomes a pause state (PAUSE). The decompression unit 32 decompresses the compressed data 101 temporarily stored in the data buffer 31 in the playback state (PLAY), and outputs the decompressed image 300 to a display device (not shown).

  In the pause state (PAUSE), the decompression process is continued until the compressed data 101 in the data buffer 31 becomes reversible compressed data, that is, until a decompressed decompressed image 300 is output to a display device (not shown).

  When the command transmission unit 33 transmits the session end command, the expansion by the expansion unit 32 and the reception by the reception unit 30 are stopped, and the data remaining in the data buffer 31 is discarded. Then, the state of the image receiving device 3 returns to the initial state (INIT) again.

  FIG. 9 is a flowchart showing processing of the receiving unit 30. The processing of the reception unit 30 starts from a state in which a session start command is input from a UI (not shown) and the command transmission unit 33 transmits the session start command as the command 103 to the transmission side.

  In the data buffer 31, the receiving unit 30 initializes bufptr indicating the head address for storing the compressed data 101 and stored_Idx indicating the index of the data buffer 31 to store (S901). For example, bufptr = 0 and stored_Idx = 0 may be set.

  The receiving unit 30 determines whether the session has ended (S902). If the determination in step S902 is YES (end of session), the process ends. If the determination in step S902 is NO (session has not ended), the receiving unit 30 determines whether or not there is an empty space in the data buffer 31 (S903). This determination can be performed by the same method as in step S301 in FIG.

  If the determination in step S903 is NO (no space available), the receiving unit 30 waits for a certain time (S910), and the process proceeds to step S902. If the determination in step S903 is YES (there is an empty space), the receiving unit 30 determines whether the image receiving device 3 is in a playback state (PLAY) or a pause state (PAUSE) (S904). If the determination in step S904 is NO (not a playback state or a pause state), the process proceeds to step S910.

  When the determination in step S904 is YES (reproduction state or pause state), the receiving unit 30 receives the packet header (S905). The receiving unit 30 receives data for the payload size (S906). As shown in FIG. 3, the packet header includes a payload size.

  If the packet size, frame head information, and frame end information shown in FIG. 3 are deleted from the packets received in steps S905 and S906, a part of the compressed data 101 is obtained.

  The receiving unit 30 stores the compressed data 101 at the address indicated by the stored_Idx-th bufptr in the data buffer 31, and increments the bufptr by the size of the compressed data (S907). Then, the receiving unit 30 determines whether or not the compressed data 101 is the end of the compressed data of one frame based on the value of end_flag included in the frame end information (S908).

  If the determination in step S908 is YES (end) (that is, if end_flag is TRUE), the receiving unit 30 updates stored_Idx indicating an index to be stored next, and sets bufptr to 0 (S909). ), And the process proceeds to step S902. For example, when stored_Idx <N, the reception unit 30 may set a value obtained by adding 1 to stored_Idx, and may set 0 to 0 when stored_Idx is N. If the determination in step S908 is NO (not the end), the process proceeds to step S902.

  The processing of the receiving unit 30 has been described above.

  FIG. 10 is a flowchart showing processing of the decompression unit 32. The processing of the decompression unit 32 starts from a state in which a session start command is input from a UI (not shown) and the command transmission unit 33 transmits the session start command as the command 103 to the transmission side.

  The decompressing unit 32 initializes the value of data_idx (S1001). The decompressing unit 32 determines whether or not the session has ended (S1002). If the determination in step S1002 is YES (end of session), the process ends.

  If the determination in step S1002 is NO (session has not ended), the decompression unit 32 sets a timer (S1003). Here, the value set in the timer may be designated by a UI or the like, or a frame interval calculated based on a preset frame rate may be designated. For example, when the frame rate is set to 30 fps, the timer value is set to 33 ms.

  The decompressing unit 32 determines whether the compressed data 101 is stored in the data_Idx-th index (buf [data_Idx]) of the data buffer 31 (S1004). If the determination in step S1004 is NO (compressed data is not stored), the decompression unit 32 waits for the timer to expire (S1012), and transitions to step S1002.

  If the determination in step S1004 is YES (compressed data is stored), the decompressing unit 32 determines whether the image receiving device 3 is in a playback state or a paused state (S1005). If the determination in step S1005 is NO (not a playback state or a pause state), the process proceeds to step S1012.

  When the determination in step S1005 is YES (reproduction state or pause state), the decompressing unit 32 determines whether or not the progressive mode is set (S1006). If the determination in step S1006 is YES (progressive mode), the decompression unit 32 determines whether or not the compressed data 101 stored in buf [data_Idx] has been received (min_size) bytes or more (that is, out of the compressed data 101) , Whether or not all data that cannot be discarded is received (S1007).

  If the determination in step S1007 is NO (not received), the process proceeds to step S1012. If the determination in step S1007 is YES (received), the decompression unit 32 decompresses the compressed data 101 stored in buf [data_Idx]. The decompressing unit 32 outputs the decompressed decompressed image 300 to, for example, a display device (S1009). Here, the output destination of the decompressed image is the display device, but is not limited thereto. For example, the data may be output to an auxiliary storage device such as a hard disk.

  At this time, the compressed data 101 supplied to the decompression unit 32 may be supplied up to the point where it can be received from the beginning, or only the data received after the data inputted in the previous decompression may be inputted.

  When the determination in step S1006 is NO (full frame mode), the decompression unit 32 determines whether or not the end_flag of the compressed data 101 stored in buf [data_Idx] is TRUE (that is, the compressed data 101 of the frame). (S1008). When the determination in step S1008 is YES (reception has been completed), the process proceeds to step S1009. If the determination in step S1008 is NO (not received), the process proceeds to step S1012.

  After step S1009, the decompression unit 32 determines whether or not the end_flag of the compressed data 101 stored in buf [data_Idx] is TRUE (that is, whether or not reception of the compressed data 101 of the frame has been completed). Determination is made (S1010). If the determination in step S1010 is YES (reception has been completed), the decompression unit 32 discards the compressed data stored in buf [data_Idx] and updates the value of data_Idx (S1011). The method for updating data_Idx is the same as the method for updating stored_Idx in step S909 of FIG. If the determination in step S1010 is NO (no reception has been completed), the process proceeds to step S1012.

  The processing of the decompression unit 32 has been described above.

  The present embodiment has been described above.

  According to the present embodiment, when the progressive mode is selected, even if the compressed data for one frame is received only halfway, it can be sequentially expanded and displayed according to the designated frame rate.

  In addition, when lossless mode is selected, compressed data transmitted lossless can be expanded and displayed in progressive mode or full frame mode, and when lossy mode is selected, the frame rate is maintained by transmission abort processing. Thus, the compressed data transmitted can be received and reproduced while maintaining the frame rate.

  Even when a pause instruction is issued, a reversible image finally transmitted from the transmission side can be displayed by performing decompression display processing at a frame interval or the like based on the designated frame rate. .

  In addition, even when a still image is input on the transmission side, the compressed data of the frame being transmitted is transmitted to the end until the transmission side inputs another different image. By performing decompression / display processing at intervals or the like, it becomes possible to transmit compressed data that is more reversible. If the still time continues, a reversible image can be expanded and displayed finally.

(Explanation of effect)
FIG. 11 is an explanatory diagram of the effect of the system using the image transmission device 1 and the image reception device 3. FIG. 11 is a schematic diagram when a compressed stream that can be truncated from the end is compressed and transmitted from frame 0 at an interval of, for example, 33 ms. Each rectangle represents a compressed stream, and the horizontal length is the data length.

  For example, if all the compressed streams of frame 0 are transmitted, losslessness is obtained, and if a certain point is transmitted, an expanded image having a predetermined image quality is obtained. The more data that is transmitted, the better the image quality and the more reversible decompressed image is obtained.

  As a conventional example of a compression transmission method using such a compression method, FIG. 11 shows three examples. Conventional example 1 is a transmission method that prioritizes the frame rate. For example, the frame rate is maintained by transmitting data with a data size that can be transmitted at an interval of 33 ms under the band. In this method, a pause instruction is issued. Even in such a case, only a part of the compressed data is transmitted, so that the image quality of the image displayed at the time of pause is lowered.

  Conventional example 2 is a method of transmitting all images losslessly. If transmission cannot be made within the frame interval, the frame is skipped or the next frame is not transmitted until one frame is transmitted. In such a transmission method, it is possible to always display an image without loss, but the frame rate cannot be maintained.

  Conventional example 3 (Patent Document 1) is a method of performing transmission while satisfying a predetermined image quality. Transmission can be performed with high image quality while maintaining a certain frame rate. It can only be transmitted in a lossless manner, and the image cannot be displayed losslessly, and the frame rate cannot be maintained.

  The system using this embodiment shown in FIG. 11 can transmit while maintaining the frame rate, and can transmit and display a lossless image when a pause command is input. It becomes.

  FIG. 12 is an explanatory diagram of the effect of the system using the image transmission device 2 and the image reception device 3.

FIG. 12 shows an example in which frames 2, 3, 4,... (N-1) are still images. Since conventional example 3 shown in FIG. 11 does not determine a still image, even if a still image is input, it can be displayed only with a predetermined image quality.

  In the system using this embodiment, after transmission of frame 2 is started, frames 3 to (n−1) are determined as still images, and transmission of compressed data of frame 2 is continued without compression. The compressed data of frame2 is transmitted until it becomes lossless.

  Further, when the progressive mode is selected in the image receiving device 3, the image of frame 2 can be displayed at high speed by performing expansion / display processing based on the frame interval, and the image quality is gradually increased until the display image becomes lossless. Can be reproduced so that

  As described above, according to the above-described embodiments, it is possible to provide an image transmission apparatus and method, and an image reception apparatus and method that can transmit a higher quality image while reducing transmission delay.

  Note that the image transmission device and the image reception device can also be realized by using, for example, a general-purpose computer device as basic hardware. That is, the input unit 10, the compression unit 11, the transmission unit 12, the command reception unit 13, the determination unit 14, the determination unit 24, the command transmission unit 33, the image reception unit 30, and the decompression unit 32 are mounted on the computer device. This can be realized by causing a processor to execute a program. The data buffer 121, the data buffer 31, and the image buffer 25 can be realized in a memory or the like mounted on the computer device. At this time, the image transmission device and the image reception device may be realized by installing the above program in a computer device in advance, or may be stored in a storage medium such as a CD-ROM or via a network. You may implement | achieve by distributing a program and installing this program in a computer apparatus suitably. Further, the data buffer 121, the data buffer 31, and the image buffer 25 are a memory, a hard disk or a storage medium such as a CD-R, a CD-RW, a DVD-RAM, and a DVD-R, which are built in or externally attached to the computer device. It can be realized by appropriately using the above.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1, 2 Image transmitter 3 Image receiver 10 Input part 11 Compression part 12 Transmission part 13 Command reception part 14, 24 Determination part 25 Image buffer 30 Reception part 31, 121 Data buffer 32 Expansion part 122 Data transmission part

Claims (10)

An image transmitting apparatus that transmits a compressed moving image to a receiving side,
A compression unit that reversibly compresses an input image and obtains compressed data of the image;
A transmitter that sequentially transmits the compressed data as a data packet divided into a plurality of bits from the upper bit side;
A determination unit that determines whether or not the display of the image is stopped for a certain time or more on the receiving side,
When the determination unit determines that the display of the image is stopped for a certain time or more on the reception side, the transmission unit continues transmission of the compressed data being transmitted.
Image transmission device. A command receiving unit for receiving a command from the receiving side;
The command is
Contains a play command that indicates whether the transmission is in play or paused state,
The determination unit
The image transmission device according to claim 1, wherein when the reproduction command is in a paused state, the reception side determines that the display of the image is stopped for a predetermined time or more. The command includes a transmission mode indicating a lossless mode in which all the compressed data is transmitted or a lossy mode in which lossy compressed data in which lower-order bits of the compressed data are truncated is transmitted,
The determination unit
The image transmission device according to claim 1, wherein when the transmission mode is a lossless mode, the reception side determines that display of the image is stopped for a predetermined time or more. The determination unit
The image transmission device according to claim 1, wherein when a plurality of consecutive images input to the compression unit are substantially the same, the receiving side determines that the display of the image is stopped for a predetermined time or more. The compressed data includes data that cannot be truncated and data that can be truncated.
5. The image transmission device according to claim 1, wherein the determination unit determines that the display of the image is stopped for a predetermined time or more on the reception side while the transmission unit is transmitting data that cannot be discarded. The transmitter is
Frame head information indicating whether or not the data packet of the compressed data is the head of the compressed data, and frame end information indicating whether or not the data packet is end data when transmission of the compressed data is stopped; 6. The image transmitting apparatus according to claim 1, wherein lossless information indicating whether or not the end of the compressed data is added to the head of the compressed data and transmitted. An image receiving device that receives a moving image from a transmission side,
A receiving unit that sequentially receives a part of the compressed data of each frame of the moving image from the beginning;
Based on the playback mode indicating whether it is a progressive mode or not, select whether to decompress a part of the compressed data of one frame already received at an arbitrary timing, or to decompress after receiving all of the compressed data, A decompression unit for decompressing the received compressed data;
A command transmission unit for transmitting a reproduction command indicating whether the reproduction state or the pause state to the transmission side;
When the transmission command transmission unit transmits the reproduction command in a paused state, the reception unit continues to receive the compressed data until all the compressed data being received is received,
The decompressing unit is an image receiving device that continues decompressing the received compressed data. If the playback mode is not progressive mode,
The decompression unit decompresses after receiving all the compressed data of one frame,
When the playback mode is progressive mode,
The image receiving apparatus according to claim 7, wherein the decompressing unit decompresses a part of the received compressed data. An image transmission method for transmitting a compressed moving image to a receiving side,
Reversibly compress the input image to obtain the compressed data of the image,
The compressed data is sequentially transmitted as a data packet divided into a plurality from the upper bit side,
It is determined whether the display of the image is stopped for a certain time or more on the receiving side,
When it is determined that the display of the image is stopped for a certain time or more on the receiving side, the transmission of the compressed data being transmitted is continued.
Image transmission method. An image receiving method for receiving a moving image from a transmission side,
Receive a part of the compressed data of each frame of the moving image sequentially from the beginning,
Based on the playback mode indicating whether it is a progressive mode or not, select whether to decompress a part of the compressed data of one frame already received at an arbitrary timing, or to decompress after receiving all of the compressed data, Decompress the received compressed data,
Send a playback command to the sending side indicating whether playback or pause,
When transmitting the playback command in a pause state, at the time of reception, the reception of the compressed data is continued until all the compressed data being received is received,
An image receiving method in which decompression of the received compressed data is continued during the decompression.