Recorded MP4 - Audio out of sync in Chrome and Quicktime
We're having a very odd problem here and I'd really appreciate your help. I'll get deep into the details, so that you can understand what's going on.
We have a live 720p MP4 video streaming from Wirecast 6.0.4 via RTMP to a Wowza Server 4.2.0. The video stream is then distributed via AWS Cloud Front to end users via HTTP. All working fine.
While it is streaming, Wirecast records to disk, using the very same specs as the stream. Wowza also records "what it gets" from the encoder. This means that we get a "local copy" on the Encoder (recorded by Wirecast) and a "server copy" on the server (recorded by Wowza).
While we watch it live, everything is perfect. Audio is in sync. All fine. However, when we watch the archived file in Chrome, we notice that the video recorded by Wowza is not in sync with the audio. We download the actual file and play it locally in Chrome, and problem persists. Note that this happens *only* in Chrome and Quicktime player. If I open the file on VLC or Media Player, audio sync is perfect on the very same file.
Please note that this only occurs on the video recorded by Wowza. The video recorded by Wirecast is perfectly synched.
In other words, it seems that Chrome "does not like" the video recorded by Wowza (although it has no problem playing its live version). Please also note that the audio quality and video quality are fine. The only problem is the audio delayed by around 1/2 second. It appears that the culprit is actually Chrome itself, but I cannot find a workaround for this. Any ideas?
Wowza places the moov atom at the end of the file rather than the beginning. With progressive download this can be a problem as you need to download the file completely before playback.
Please test the recording with on of Wowza's sample players. You can find them in the [wowza-install]/examples directory. If you still notice a/v sync please open a ticket with support by following this guide and sending requested information to
firstname.lastname@example.org. Please also include a sample recording with a/v sync issue: