• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 98 subscribers
  • Views 816 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Could DM368 support PC USB camera (1080p) and how?

zhaozhuo lee
Prodigy 30 points

hi everyone,

I 'd like to take DM368 to capture video from PC USB camera, and encode it to specific H.264 format. The DM368 should be doing 1080p H.264 encoding all the time. (so, the HDVICP unit is already used.)

 I had some thought and come up with further questions, First ly, if the data from USB is encoded, we shall first decode it .

1. what algrithm does most PC usb camera use?   raw data, YUY2, Motion-JPEG, and else? any new kind? If H.264, how to deal with the decode ? (note: 1 HDVICP already being encoding)

2. could DM368 handle 1080p MJPEG decode?  (the MJCP could do the 1080p MJPEG?)

thanks !

  • 0
    TI__Mastermind 19985 points

    Hi,

    With one DM368, if you are doing 1080P 30fps H.264 encoding, then it is almost comsuming all the available processing. We might not be able to do any MJPEG decoding.

    Raw or YUV capture over USB interface for a 1080P stream is not possible because of the USB bandwidth limitations. Generally it would need UVC class and with the earlier mentioned formats, with the UVC class we cannot achieve the bandwidth.

    MJPEG would be an option and availble on current webcams too. But as i said earlier, if you want one 1080P30 H.264 encoding continuously, then this option is also not possible. MJPEG decoder on DM368 can do 1080P decode.

    So my question would be that are you willing to being down the framerate of capture and encoding? If yes, we can propose a solution using DM368.

    Regards,

    Anshuman

    PS: Please mark this post as verified, if you think it has answered your question. Thanks.

  • 0 in reply to Anshuman Saxena
    TI__Mastermind 19985 points

    Hi,

    Could you proceed further on this analysis? Let us know if you need further information.

    Regards,

    Anshuman

    PS: Please mark this post as verified, if you think it has answered your question. Thanks.

  • 0 in reply to Anshuman Saxena
    Prodigy 30 points

    hi Anshuman ,

    Thanks so much for  your kind reply.

    1. From datasheet, DM368 has too co-processor. One is HDVICP, for H.264/AVC/VC-1; and one MJCP for Jpeg/MPEG/Motion-JPEG. So, I assume it's feasible that the DM368 encode the H.264 @1080,30 while decode the MJPEG @1080,30.  Can you plz further clarify if any misunderstanding?

    2. With MJPEG, I think USB2.0 Bandwidth is not a fatal limit for 1080p. Typical MJPEG compress ratio is 10:1, and 1920*1080*24*30=1.5Gbps, thus the bandwidth after compression is 150Mbps. I think this should be reachable by USB2.0.   Actually there is 1080p USB2.0 PC Camera in market, like Logitech C910.
    http://www.logitech.com/zh-tw/webcam-communications/webcams/devices/6816 

    Actually I am not sure what compression algorithm the C910 uses. And I also have no idea about other USB 2.0 HD cameras. Generally I see  RGB24,YUY,YV12,MJPEG for 0.3M pixel cameras, but what  for HD? I captured some C910 session by "USB Trace", but I don't know Software much, can you help to check its format?

     

  • 0 in reply to zhaozhuo lee
    TI__Mastermind 19985 points

    Hi,

    zhaozhuo lee said:
    1. From datasheet, DM368 has too co-processor. One is HDVICP, for H.264/AVC/VC-1; and one MJCP for Jpeg/MPEG/Motion-JPEG. So, I assume it's feasible that the DM368 encode the H.264 @1080,30 while decode the MJPEG @1080,30.  Can you plz further clarify if any misunderstanding?

    We do have separate engines, but running 1080P30 H.264 needs lot of DDR bandwidth and EDMA channels. With this, you cannot run JPEG in parallel. Actually, to retain performance of 1080P30 H.264, MJPEG cannot run at all mainly due to limited DDR bandwidth. It is not a usecase for DM368.

    zhaozhuo lee said:
    2. With MJPEG, I think USB2.0 Bandwidth is not a fatal limit for 1080p. Typical MJPEG compress ratio is 10:1, and 1920*1080*24*30=1.5Gbps, thus the bandwidth after compression is 150Mbps. I think this should be reachable by USB2.0.   Actually there is 1080p USB2.0 PC Camera in market, like Logitech C910.
    http://www.logitech.com/zh-tw/webcam-communications/webcams/devices/6816 

    The camera you are referring to most likely would be doing H,264 1080P30 processing. 150Mbps is still high on USB. Generally, all HD cameras would be using compression like H.264

     

    Regards,

    Anshuman

    PS: Please mark this post as verified if you think it has answered your question. Thanks.

  • 0 in reply to Anshuman Saxena
    Prodigy 30 points

    hi Anshuman,

    1. Get it. If we lower the limit for framerate, like 24fps, is it possible? 
         I assumed the MJPEG decode would not take too much DDR bandwidth as it is frame-independent. But I have no explicit picture about the bandwidth duty cycle.

    2. sorry to hear that:) Because it makes mission impossible. But allow for more questions, when I use C910 to display/capture, is my PC(to be more clear, the C910 driver) decoding 1080p? actually the CPU usage percentage is not high. (using CPU L7500,1.6G dual, within 10%)

    thanks and wish you all day happy~