HW H264 adds useless SEI on each frame. It takes 5% of bitrate for 100kbps 30fps video. |
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Issue descriptionChrome Version: 64.0.3282.87 Chrome OS: 10176.47.0 Device: HP Kip What steps will reproduce the problem? 1. Make video call and dump video received from Kip. I used custom build of Chromium on Ubuntu where I enabled dumping of received video (patch is attached). 2. Open https://appr.tc/?vrc=h264&vrbr=200&vsc=h264&vsbr=200 in Chromium from (1). 3. Join the room from Kip. 4. Analyze received.ivf which you will find in the folder you ran chromium from. What is the expected result? Video stream contains NAL units of type 7,8,5 and 1 (SPS, PPS, IDR and slice). What happens instead? In addition to SPS/PPS/IDR/Slice video stream contains NAL units type 6: each frame is accompanied with buffering_period and pic_timing SEI. Those SEI adds 20 bytes to each frame. For 30fps video coded into 100kbps this will be 5% of total bitrate (i.e. something). These is no need to send those SEI since there are not needed for decoding. Please use labels and text to provide additional information. For graphics-related bugs, please copy/paste the contents of the about:gpu page at the end of this report.
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Jan 30 2018
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Jan 30 2018
I reproduced the issue on Kip and added some logs to look into what is happening. - VAAPI VEA forces a keyframe if(frame_ref->force_keyframe || encoding_parameters_changed_)[0]. - WebRTC asks for RequestEncodingParametersChange() too often which in turn sets |encoding_parameters_changed_| true and forces a keyframe. - It looks like there wasn't a change on VAAPI side lately. This is probably caused by WebRTC asking more often. - It looks like most param change is in framerate: between 29 and 30. Logs are attached. posciak@ can you comment if it is necessary to force keyframe in each param change? [0] https://cs.chromium.org/chromium/src/media/gpu/vaapi/vaapi_video_encode_accelerator.cc?rcl=8bbeef73d50a85e6672204d6c5a8638249e244a8&l=655
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Jan 30 2018
Issue 801493 has been merged into this issue.
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Jan 31 2018
It seems #3 and #4 are not related to this issue, which is is about SEI. Ticket for frequent intra is here - https://bugs.chromium.org/p/chromium/issues/detail?id=806235. |
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Comment 1 by ssilkin@chromium.org
, Jan 29 201851.1 KB
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