Thanks for the prompt response - I had actually tried MJPEG in mencoder (not sure how to test it in ffmpeg); but for some reason it allocates the same exact bandwidth as well, no matter what resolution, codec (mjpeg or yuv), or frame rate. If you can provide any insight into this or suggest any other methods of testing I would greatly appreciate it. Once again, I'd like to thank you for your time.
--- 320x240, 5fps, MJPG: cvlc -vv v4l2:///dev/video0 :v4l2-vdev="/dev/video0" :v4l2-width=320 :v4l2-height=240 :v4l2-fps=5 :v4l2-caching=300 :v4l2-chroma=MJPG --no-plugins-cache --album-art=0 [chopped output] [0xb6300c08] v4l2 demux debug: using streaming i/o (mmap) [0xb6300c08] v4l2 demux debug: trying specified size 320x240 [0xb6300c08] v4l2 demux debug: Driver requires at most 153600 bytes to store a complete image [0xb6300c08] v4l2 demux debug: Interlacing setting: progressive [0xb6300c08] v4l2 demux debug: supported frame intervals for MJPG, 320x240: [0xb6300c08] v4l2 demux debug: supported frame interval: 1/30 [0xb6300c08] v4l2 demux debug: supported frame interval: 1/20 [0xb6300c08] v4l2 demux debug: supported frame interval: 1/15 [0xb6300c08] v4l2 demux debug: supported frame interval: 1/10 [0xb6300c08] v4l2 demux debug: supported frame interval: 2/15 [0xb6300c08] v4l2 demux debug: added new video es MJPG 320x240 [0xb6500608] main input debug: selecting program id=0 [0xb6300c08] v4l2 demux debug: User set fps=5.000000 [0xb6300c08] main demux debug: using access_demux module "v4l2" [0xb6300c08] main demux debug: TIMER module_need() : 260.411 ms - Total 260.411 ms / 1 intvls (Avg 260.411 ms) [0xb63019b0] main decoder debug: looking for decoder module: 39 candidates [0xb63019b0] avcodec decoder debug: libavcodec initialized (interface 0x342900) [0xb63019b0] avcodec decoder debug: using direct rendering [0xb63019b0] avcodec decoder debug: ffmpeg codec (Motion JPEG Video) started [0xb63019b0] main decoder debug: using decoder module "avcodec" [0xb63019b0] main decoder debug: TIMER module_need() : 2.954 ms - Total 2.954 ms / 1 intvls (Avg 2.954 ms) [0xb63019b0] main decoder debug: thread (decoder) created at priority 0 (input/decoder.c:315) [0xb63019b0] main decoder debug: thread started [0xb6500608] main input debug: `v4l2:///dev/video0' successfully opened -- dmesg: uvcvideo: Device requested 3072 B/frame bandwidth. uvcvideo: Allocated 5 URB buffers of 32x3072 bytes each. ----- 1280x800, 30FPS, mjpeg: cvlc -vv v4l2:///dev/video0 :v4l2-vdev="/dev/video0" :v4l2-width=1280 :v4l2-height=800 :v4l2-fps=30 :v4l2-caching=300 :v4l2-chroma=MJPG --no-plugins-cache --album-art=0 [0xb6600e90] v4l2 demux debug: trying specified size 1280x800 [0xb6600e90] v4l2 demux debug: Driver requires at most 1843200 bytes to store a complete image [0xb6600e90] v4l2 demux debug: Interlacing setting: progressive [0xb6600e90] v4l2 demux debug: supported frame intervals for MJPG, 1280x720: [0xb6600e90] v4l2 demux debug: supported frame interval: 1/30 [0xb6600e90] v4l2 demux debug: supported frame interval: 1/20 [0xb6600e90] v4l2 demux debug: supported frame interval: 1/15 [0xb6600e90] v4l2 demux debug: supported frame interval: 1/10 [0xb6600e90] v4l2 demux debug: supported frame interval: 2/15 [0xb6600e90] v4l2 demux debug: added new video es MJPG 1280x720 [0xb6700608] main input debug: selecting program id=0 [0xb6600e90] v4l2 demux debug: User set fps=30.000000 [0xb6600e90] main demux debug: using access_demux module "v4l2" [0xb6600e90] main demux debug: TIMER module_need() : 252.439 ms - Total 252.439 ms / 1 intvls (Avg 252.439 ms) [0xb6601c58] main decoder debug: looking for decoder module: 39 candidates [0xb6601c58] avcodec decoder debug: libavcodec initialized (interface 0x342900) [0xb6601c58] avcodec decoder debug: using direct rendering [0xb6601c58] avcodec decoder debug: ffmpeg codec (Motion JPEG Video) started [0xb6601c58] main decoder debug: using decoder module "avcodec" [0xb6601c58] main decoder debug: TIMER module_need() : 2.521 ms - Total 2.521 ms / 1 intvls (Avg 2.521 ms) [0xb6601c58] main decoder debug: thread (decoder) created at priority 0 (input/decoder.c:315) [0xb6601c58] main decoder debug: thread started [0xb6700608] main input debug: `v4l2:///dev/video0' successfully opened ------ dmesg: uvcvideo: Device requested 3072 B/frame bandwidth. uvcvideo: Allocated 5 URB buffers of 32x3072 bytes each. ----- 1280x800, 30fps, YUY2: [0xb6a00e90] v4l2 demux debug: using streaming i/o (mmap) [0xb6a00e90] v4l2 demux debug: trying specified size 1280x800 [0xb6a00e90] v4l2 demux debug: Driver requires at most 2048000 bytes to store a complete image [0xb6a00e90] v4l2 demux debug: Interlacing setting: progressive [0xb6a00e90] v4l2 demux debug: supported frame intervals for YUY2, 1280x800: [0xb6a00e90] v4l2 demux debug: supported frame interval: 1/10 [0xb6a00e90] v4l2 demux debug: added new video es YUY2 1280x800 [0xb6b00608] main input debug: selecting program id=0 [0xb6a00e90] v4l2 demux debug: User set fps=30.000000 [0xb6a00e90] main demux debug: using access_demux module "v4l2" [0xb6a00e90] main demux debug: TIMER module_need() : 253.072 ms - Total 253.072 ms / 1 intvls (Avg 253.072 ms) [0xb6a01c58] main decoder debug: looking for decoder module: 39 candidates [0xb6a01c58] rawvideo decoder warning: invalid frame rate 0/0, using 25 fps instead [0xb6a01c58] main decoder debug: using decoder module "rawvideo" [0xb6a01c58] main decoder debug: TIMER module_need() : 0.836 ms - Total 0.836 ms / 1 intvls (Avg 0.836 ms) [0xb6a01c58] main decoder debug: thread started [0xb6a01c58] main decoder debug: thread (decoder) created at priority 0 (input/decoder.c:315) [0xb6b00608] main input debug: `v4l2:///dev/video0' successfully opened dmesg: uvcvideo: Device requested 3072 B/frame bandwidth. uvcvideo: Allocated 5 URB buffers of 32x3072 bytes each. ----------------------- On Sun, Jan 10, 2010 at 8:30 PM, Laurent Pinchart < laurent.pinch...@ideasonboard.com> wrote: > Hi Seth, > > On Wednesday 06 January 2010 03:54:11 Seth W wrote: > > Here you are. Thanks in advance for your assistance. (PS - Please note > > there are two cameras, both same make/model therefore share the same ID) > > Thanks for the information. The device supports the following bandwidths > (unrelated information removed for the sake of clarity): > > > wMaxPacketSize 0x0080 1x 128 bytes > > wMaxPacketSize 0x0100 1x 256 bytes > > wMaxPacketSize 0x0200 1x 512 bytes > > wMaxPacketSize 0x0400 1x 1024 bytes > > wMaxPacketSize 0x0c00 2x 1024 bytes > > wMaxPas.cketSize 0x1400 3x 1024 bytes > > Your previous e-mail included an excerpt from the kernel log clearly > showing > that the device asked for 3x 1024 bytes per microframe in both 640x480 and > 1280x800. > > The default frame rate at those resolutions is 30fps and 10fps > respectively. > As every pixel takes 2 bytes in uncompressed YUV, this leads to > > 640*480*2*30 = 18000 KiB/s > 1280*800*2*10 = 20000 KiB/s > > Divided by 8000 microframes per second, we get > > 640x480 -> 2304 bytes / microframe > 1280x800 -> 2560 bytes / microframe > > The lowest bandwidth compatible with those values is 3x 1024 bytes per > microframe, which is too high to stream from both cameras at the same time. > > You could try lowering the frame rate. The average required bandwidth will > be > lower, but the device might not have enough internal memory to store a > complete frame and smooth bandwidth usage. In that case it will still ask > for > a high bandwidth, and streaming from two devices simultaneously will fail. > > The other option is to use MJPEG instead of YUV. That will reduce the > bandwidth requirements drastically, but you will have to decompress the > MJPEG > stream > > -- > Regards, > > Laurent Pinchart >
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