Constant Audio Delay With HTTP HLS Streaming

Wowza Streaming Engine
1

Hi,

(tl;dr We have a problem with certain mp4 files which always stream with a 0.5 second audio delay from beginning to end.)

We have a substantial archive (about 1.2 million files) of video files consisting of h.264 video + mp3 audio in a .flv

container. We currently stream these on-demand using rtmp. We would like to remux these files to mp4 for streaming via http (cupertino).

We have carried out a number of tests using

  • various demuxers/remuxers (ffmpeg and MP4Box), and various muxing parameters

  • various input samples

    In each case we find exactly the same behaviour

  • the mp4 file plays fine on a local vlc

  • when streamed via wowza (v4.0.3) the sound is delayed by 0.5 seconds. The delay appears to be very close to exactly 0.5 seconds, for all files tested, and throughout the whole file (which may be more than an hour long). There is no drifting [NOTE: now upgraded to 4.4.1 with the same results.].

  • If we download one of the chunk .ts-files and play that locally then the audio is already delayed by 0.5 seconds in the chunk.

    So it looks as if the part of wowza that chunks the files is introducing the audio delay. Any ideas? Here are

    links to an mp4 file which plays fine locally but streams with the audio delay, and a chunk.ts file (downloaded from wowza by curl’ing) which shows the delay.

    https://www.dropbox.com/s/hwtxownke63a6wf/debatten.bart.10.mp4?dl=0

    https://www.dropbox.com/s/i0pyf36e9tl71uq/media_w1112261523_0.ts?dl=0

    Colin Rosenthal

    State And University Library

    Aarhus, Denmark

2

For anyone else interested:

Wowza Support have responded to this issue by pointing me to https://www.wowza.com/docs/how-to-use-ffmpeg-with-wowza-media-server-mpeg-ts which correctly describes the problem and provides a usable solution/workaround.

Colin Rosenthal

State And University Library

Aarhus, Denmark

3

Hi Colin,

I’m glad you found the information you needed and the issue is now resolved.

Thanks for sharing this in the update for others to benefit from.

Regards,

Jason