MediaRecorder: produce keyframes more often.
Reported by
thembr...@gmail.com,
Mar 11 2016
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Issue descriptionExample URL: Steps to reproduce the problem: Currently MediaRecorder forces keyframes every 30000 frames. This makes it prohibitively expensive to seek in a resulting video (without re-encoding), as this might require decoding up to 30000 frames. Forcing more keyframes makes seeking much more efficient. To see performance difference, record something on https://www.cam-recorder.com/ and try to seek in resulting file. It writes MediaRecorder output, but adds missing Cues/Duration elements to the WebM file to allow seeking. What is the expected behavior? MediaRecorder should produce keyframes more often. Seeking should be possible without re-encoding at decent performance. What went wrong? Seeking in a video without keyframed is very slow. Did this work before? No Is it a problem with Flash or HTML5? N/A Does this work in other browsers? Yes Chrome version: 49.0.2623.91 Channel: stable OS Version: Flash Version: See https://codereview.chromium.org/1782043003/ for existing discussion
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Mar 14 2016
The following revision refers to this bug: https://chromium.googlesource.com/chromium/src.git/+/10fd187c1de8dff86eb165deaecec7a5b5f6cc36 commit 10fd187c1de8dff86eb165deaecec7a5b5f6cc36 Author: thembrown <thembrown@gmail.com> Date: Mon Mar 14 22:25:09 2016 Force keyframes every 100 frames. Old behavior forced keyframes every 30000 frames. This makes it prohibitively expensive to seek in a resulting video (without re-encoding), as this might require decoding up to 30000 frames. Forcing more keyframes makes seeking much more efficient. BUG= 594241 Review URL: https://codereview.chromium.org/1782043003 Cr-Commit-Position: refs/heads/master@{#381090} [modify] https://crrev.com/10fd187c1de8dff86eb165deaecec7a5b5f6cc36/content/renderer/media/video_track_recorder.cc
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Mar 15 2016
thembrown@gmail.com. Thanks for providing fix. Please resolve this bug once your fix is accepted.
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Mar 15 2016
I probably don't have permissions to mark as fixed.
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Mar 29 2016
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Jun 14 2016
This is going to tank quality; did anyone do any before and after comparisons to see what the quality hit was like, especially when restricting video bitrate? Why is 100 frames the correct value? Is there a noticeable keyframe refresh every 100 frames? Keyframes are the most expensive type of frame; in general it's best to let the encoder decide if inserting one makes sense. |
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Comment 1 by rsgav...@chromium.org
, Mar 11 2016Labels: triage-te