New: Drop is video frame rate in kernel .34
A message that is not in the archive (sent off-list or not yet received): [email protected]/
Quoted 1 line · On Sun, 30 May 2010 14:29:55 GMT [email protected] wrote:
2.6.33 -> 2.6.34 performance regression in dvb webcam frame rates.
Em 02-06-2010 18:09, Andrew Morton escreveu:
Quoted 6 lines
Quoted 1 line · On Sun, 30 May 2010 14:29:55 GMT [email protected] wrote:
2.6.33 -> 2.6.34 performance regression in dvb webcam frame rates.
I don't think this is a regression. Probably, the new code is allowing a higher resolution. As the maximum bandwidth from the sensor to the USB bridge doesn't change, and a change from QVGA to VGA implies on 4x more pixels per frame, as consequence, the number of frames per second will likely reduce by a factor of 4x.
I've asked the reporter to confirm what resolutions he is setting on 2.6.33 and on 2.6.34, just to double check if my thesis is correct.
Cheers,
Mauro.
Quoted 8 lines · Mauro Carvalho Chehab
Em 02-06-2010 18:09, Andrew Morton escreveu:
Quoted 6 lines
Quoted 1 line · On Sun, 30 May 2010 14:29:55 GMT [email protected] wrote:
2.6.33 -> 2.6.34 performance regression in dvb webcam frame rates.
Quoted 7 lines
I don't think this is a regression. Probably, the new code is allowing a higher resolution. As the maximum bandwidth from the sensor to the USB bridge doesn't change, and a change from QVGA to VGA implies on 4x more pixels per frame, as consequence, the number of frames per second will likely reduce by a factor of 4x.
I've asked the reporter to confirm what resolutions he is setting on 2.6.33 and on 2.6.34, just to double check if my thesis is correct.
Well, the two video clips attached to the bug shows the same resolution but a much, much lower video (and overall) bitrate in 2.6.34. Output from mediainfo:
General
Complete name : 2.6.33-02063303-generic #02063303.ogv Format : OGG File size : 672 KiB Duration : 6s 331ms Overall bit rate : 870 Kbps
Video
ID : 20423689 (0x137A409) Format : Theora Duration : 6s 333ms Bit rate : 714 Kbps Width : 320 pixels Height : 240 pixels Display aspect ratio : 4:3 Frame rate : 30.000 fps Bits/(Pixel*Frame) : 0.310 Stream size : 552 KiB (82%) Writing library : Xiph.Org libtheora 1.1 20090822 (Thusnelda)
Audio
ID : 1459180980 (0x56F955B4) Format : Vorbis Format settings, Floor : 1 Duration : 6s 331ms Bit rate mode : Constant Bit rate : 112 Kbps Channel(s) : 2 channels Sampling rate : 44.1 KHz Stream size : 86.6 KiB (13%) Writing library : libVorbis 20090709 (UTC 2009-07-09)
General
Complete name : 2.6.34-999-generic #201005121008.ogv Format : OGG File size : 276 KiB Duration : 15s 424ms Overall bit rate : 146 Kbps
Video
ID : 12773534 (0xC2E89E) Format : Theora Duration : 15s 433ms Bit rate : 19.8 Kbps Width : 320 pixels Height : 240 pixels Display aspect ratio : 4:3 Frame rate : 30.000 fps Bits/(Pixel*Frame) : 0.009 Stream size : 37.2 KiB (14%) Writing library : Xiph.Org libtheora 1.1 20090822 (Thusnelda)
Audio
ID : 1010301390 (0x3C37F9CE) Format : Vorbis Format settings, Floor : 1 Duration : 15s 424ms Bit rate mode : Constant Bit rate : 112 Kbps Channel(s) : 2 channels Sampling rate : 44.1 KHz Stream size : 211 KiB (76%) Writing library : libVorbis 20090709 (UTC 2009-07-09)
Bjørn
Hi,
Quoted 14 lines · Bjørn Mork
Quoted 13 lines · Mauro Carvalho Chehab
Em 02-06-2010 18:09, Andrew Morton escreveu:
Quoted 6 lines
Quoted 1 line · On Sun, 30 May 2010 14:29:55 GMT [email protected] wrote:
2.6.33 -> 2.6.34 performance regression in dvb webcam frame rates.
I don't think this is a regression. Probably, the new code is allowing a higher resolution. As the maximum bandwidth from the sensor to the USB bridge doesn't change, and a change from QVGA to VGA implies on 4x more pixels per frame, as consequence, the number of frames per second will likely reduce by a factor of 4x.
Quoted 7 lines
Quoted 2 lines
I've asked the reporter to confirm what resolutions he is setting on 2.6.33 and on 2.6.34, just to double check if my thesis is correct.
Well, the two video clips attached to the bug shows the same resolution but a much, much lower video (and overall) bitrate in 2.6.34. Output from mediainfo:
I notice in the original bug report that you claim that the lower framerate clip with 2.6.34 has "much better quality", could you define this a bit better.
I think that what is happening is the code for the new (correct) sensor is setting a higher exposure value (and thus a lighter / less dark image), but setting a higher exposure value comes at the cost of framerate. As the framerate can never be higher then 1 / exposure_time_for_1_frame.
2 things:
1) Go the preferences in cheese, and see which resolutions you can select, and make sure you are using the same resolution in 2.6.34 and 2.6.33
2) Start a v4l2 control panel applet, like v4l2ucp or gtk-v4l, and try playing around with the controls (note the controls inside cheese are software not hardware controls so don't use those).
Regards,
Hans
Quoted 2 lines · Hans de Goede
I notice in the original bug report that you claim that the lower framerate clip with 2.6.34 has "much better quality", could you define this a bit better.
Sorry for the confusion, but this wasn't me. I just read the bug report.
Bjørn