1768699 - New Reddit blurry video playback

Status: NEW

(Core :: Audio/Video: Playback, defect, P2)

Description

[Asif Youssuff]

As reported on https://www.reddit.com/r/firefox/comments/ummt1m/problems_with_reddit_video_quality_on_firefox/ and elsewhere.

User says that "quality ranges from video becoming blurry to a mosaic of jpg artifacts. sometimes combined with single digit frames per second."

I don't see this issue every time on new reddit, and I never see it on old reddit (https://old.reddit.com).

Steps to reproduce:

1. Navigate to: https://www.reddit.com/r/blender/comments/umggi0/reactiondiffusion_simulations/
2. Play video

What happens:

Sometimes, the video plays back and is extremely blurry.

Expected result:

This is not a very long or bandwidth heavy video. There should be no issue playing it without artifacts.

Media profile: https://share.firefox.dev/3PdP7IT

Comment 1

[Asif Youssuff]

Attachment: about:support

Comment 2

[C.M.Chang[:chunmin]]

One user commented that the frame rate is down to 1 frame/s:

Uploaded reddit videos randomly work/dont work. The audio playback is fine, but after 8-10 seconds the video frame rate drop to 1 frame per second.

Alastor, do you know where should we look at?

Comment 3

[C.M.Chang[:chunmin]]

Set to S3 for now. Feel free to change it

Comment 4

[Alastor Wu [:alwu][PTO until 12/16]]

I couldn't browse reddit now, their server seems broken temporarily. From the profiled result, I saw a stream ID change marker on Media Supervisor #5 in the reddit process, since then we started to demux/decode low resolution video. I saw some janks between ~5s to ~9s, I wonder if those jank made Reddit think they should switch to the lower resolution video because of the bad performance.

Comment 5

[Alastor Wu [:alwu][PTO until 12/16]]

Okay, now I can reproduce the issue.

The first output sample size change happens on 4000000.

2022-05-19 21:00:04.683000 UTC - [Child 24144: MediaSupervisor #3]: D/MediaFormatReader MediaFormatReader[28b008f1900] ::ReturnOutput: Resolved data promise for Video [4000000, 4033333]
2022-05-19 21:00:04.683000 UTC - [Child 24144: MediaSupervisor #3]: D/MediaFormatReader MediaFormatReader[28b008f1900] ::ReturnOutput: change of video display size (720x720->220x220)

Before that, we received the id change and Reddit started feeding data from 4000000

2022-05-19 20:59:59.024000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaFormatReader MediaFormatReader[28b008f1900] ::HandleDemuxedSamples: Video stream id changed from:4294967295 to:0

// some other logs

2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: V/MediaSource dom::SourceBuffer[28b06706bb0] (video/mp4;codecs="avc1.4D401E")::GetBuffered: intersection=[(0.000000, 4.000000)]
2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: V/MediaSource dom::SourceBuffer[28b06706bb0] (video/mp4;codecs="avc1.4D401E")::GetBuffered: currentValue=[(0.000000, 4.000000)]
2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: D/MediaSource dom::SourceBuffer[28b06706bb0] (video/mp4;codecs="avc1.4D401E")::AppendBuffer: AppendBuffer(ArrayBuffer)
2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: D/MediaSource dom::SourceBuffer[28b06706bb0] (video/mp4;codecs="avc1.4D401E")::AppendData: AppendData(aLength=107109)
2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: D/MediaSource TrackBuffersManager[28b077ed000] ::EvictData: currentTime=0 buffered=1233kB, eviction threshold=102400kB, evict=-101061kB canevict=0kB
2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: D/MediaSource dom::SourceBuffer[28b06706bb0] (video/mp4;codecs="avc1.4D401E")::QueueAsyncSimpleEvent: Queuing event 'updatestart'
2022-05-19 20:59:59.202000 UTC - [Child 24144: Main Thread]: D/MediaSource TrackBuffersManager[28b077ed000] ::AppendData: Appending 107109 bytes
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSource TrackBuffersManager[28b077ed000] ::ProcessTasks: Process task 'AppendBuffer'
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::IsInitSegmentPresent: aLength=107109 [003a8]
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: V/MediaSourceSamples MP4ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::Init: Checking atom:'moof' @ 0
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: V/MediaSourceSamples MP4ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::Init: Checking atom:'moof' @ 0
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: V/MediaSourceSamples MP4ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::Init: Checking atom:'mdat' @ 936
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSource TrackBuffersManager[28b077ed000] ::SetAppendState: AppendState changed from WAITING_FOR_SEGMENT to PARSING_MEDIA_SEGMENT
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::IsInitSegmentPresent: aLength=107109 [003a8]
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: V/MediaSourceSamples MP4ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::Init: Checking atom:'moof' @ 0
2022-05-19 20:59:59.203000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples MP4ContainerParser[28b06867040] (video/mp4;codecs="avc1.4D401E")::ParseStartAndEndTimestamps: [4000000, 7500000]
2022-05-19 20:59:59.204000 UTC - [Child 24144: Main Thread]: D/MediaSource dom::SourceBuffer[28b06706bb0] (video/mp4;codecs="avc1.4D401E")::DispatchSimpleEvent: Dispatch event 'updatestart'
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSource TrackBuffersManager[28b077ed000] ::OnVideoDemuxCompleted: 105 video samples demuxed
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4000000,4033333] (adjusted:[4000000,4033333]), dts:4000000, duration:33333, kf:1)
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4033333,4066666] (adjusted:[4033333,4066666]), dts:4033333, duration:33333, kf:0)
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4066666,4100000] (adjusted:[4066666,4100000]), dts:4066666, duration:33334, kf:0)
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4100000,4133333] (adjusted:[4100000,4133333]), dts:4100000, duration:33333, kf:0)
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4133333,4166666] (adjusted:[4133333,4166666]), dts:4133333, duration:33333, kf:0)
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4166666,4200000] (adjusted:[4166666,4200000]), dts:4166666, duration:33334, kf:0)
2022-05-19 20:59:59.205000 UTC - [Child 24144: MediaSupervisor #2]: D/MediaSourceSamples TrackBuffersManager[28b077ed000] ::ProcessFrames: Processing video/avc frame [4200000,4233333] (adjusted:[4200000,4233333]), dts:4200000, duration:33333, kf:0)

I checked the profiled result again, and I didn't notice that we were sending any suspicious events which would cause Reddit to append low resolution video. But I did notice that there were two event callback took much times, they are mouse up and play. So my guess is that there might be some bug in their play event handler or some where, which causes Reddit sending low resolution video to us.

I will ask Reddit to see if they could help us identify where the problem is.

Comment 6

[ormandj]

I can confirm this behavior exists on multiple devices/different distributions I've tried. My current laptop has Firefox installed via Flatpak from Flathub, 101.0.1 (64-bit) on Fedora 36 with all the latest updates and an Intel video card also exhibits this exact same behavior. This does not occur with other browsers on the same OS/machine.