0

I have a video in fragmented form which is an output of an Azure Media Services Live Event (Smooth Streaming).

I'm trying to concatenate the segments to get a single MP4 file, however I've run into a A/V sync problem - no matter what I do (time-shifting/speeding up/slowing down/using FFmpeg filters), the audio delay is always floating. To get the output MP4 file, I tried concatenating the segments for video and audio streams (both at OS file level and with FFmpeg) and then muxing with FFmpeg.

I've tried everything I found on the web and I'm always ending up with exactly the same result. What's important, when I play the source from the manifest file, it's all good. That made me skim through the manifest once again, and I realized there's CodecPrivateData value which I'm not using anywhere in the process. What is it? Could it somehow help solving my problem?

user15180344
  • 60
  • 9
  • Those are parameters needed to decode the stream. Sync is related to timestamps, so not relevant. – Gyan Feb 13 '21 at 04:37
  • Thanks for clarification, Gyan, I have never worked on videos before so I don't know much on the subject matter, and the learning curve is steep... Anyway, it looks like all I can fetch from Azure are the timestamps for each keyframe - I guess that won't be of much help, will it? – user15180344 Feb 13 '21 at 05:11

1 Answers1

0

Mystery solved: the manifest file contains the list of stream discontinuities, which need to be taken into account when concatenating the streams.

user15180344
  • 60
  • 9