Mediarecorder truncates final 2-3 seconds of recorded video




5 years ago
4 years ago


(Reporter: sdrinf, Unassigned)


30 Branch
Windows 7

Firefox Tracking Flags

(Not tracked)



(2 attachments)



5 years ago
Created attachment 8444064 [details]

User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36

Steps to reproduce:

Steps to reproduce:
* Save   to a new HTML file. This short test case creates a new mediarecorder object, records 5 seconds of video from the camera, then attempts to play it back, and load up the duration of the recorded video

* Open it in a new browser

Actual results:

Duration of the recorded video fluctuates between 1-4 seconds, instead of the 5 seconds requested length

Expected results:

5 seconds of video are recorded


5 years ago
Component: Untriaged → WebRTC: Audio/Video
Product: Firefox → Core
Component: WebRTC: Audio/Video → Video/Audio: Recording
There may be an implicit assumption here that record_start() starts actually recording instantly; I don't know the media recorder code well enough to say if this is a valid test.

Comment 2

5 years ago
Manual testing showed record_start, and specifically, mediaRecorder.start() to behave responsively (the rest of the code just sets up recording & capturing). Further test nailed this down to cutting approx 1-1.5 sec from the end of videos.
Created attachment 8444273 [details]
The duration of recording blobs

I use your script to have a test on FireFox nightly linux build (2014-6-22) and the duration on control bar seems correct.
What is the test platform/version when you found this problem?

Comment 4

5 years ago
FF 30.0 (latest & currently deployed stable), Windows 7 (x64). Laptop is an Asus Eee PC 1005HA (Seashell), webcam is an USB 2.0 UVC VGA built-in one.
Could you provide the CPU usage when the recording task is running?

Comment 6

5 years ago
Steady at 70-90%:
It looks lika a duplication of Bug 994557 that fixed in FF31.
Hi SDr, 
Would you like to try nightly?

Comment 9

5 years ago
Repro with Firefox Nightly ( 33.0a1 (2014-06-24) ) failed to reproduce this error; evidencing a fix to be in the pipeline for this already. Nominating this bug dupe & closable.

If Benjamin's suspicion is correct re:dupe, and going by the timeline at  ,does this mean I can't count on fix until at least the 22nd of July? (Original itch was having a new product extension in pipeline with immediate release dates, blocked by this issue :/   )
According our release schedule, you may need to wait the next release version of firefox, or use the beta version instead.
According to those replys, set to WorkForMe after 33.0a1 nightly.
Last Resolved: 4 years ago
Resolution: --- → WORKSFORME
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