[Libav-user] Multithreaded decoding of multi-program transport streams

Adi Shavit adishavit at gmail.com
Sun Dec 1 11:43:27 CET 2013

Does anyone have any insights or some references I should follow regarding
this issue?

On Tue, Nov 26, 2013 at 9:15 PM, Adi Shavit <adishavit at gmail.com> wrote:

> Hi,
>   I am consuming a multi-program transport stream with several video
> streams and decoding them simultaneously. This works well.
> I am currently doing it al on a single thread.
> Each AVPacket received by av_read_frame() is checked for the relevant
> stream_index and passed to a *corresponding* decoder.
> Hence, I have one AVCodecContext per decoded elementary stream. Each such
> AVCodecContext handles one elementary stream, calling
> avcodec_decode_video2() etc.
> The current single threaded design means that the next packet isn't
> decoded until the one before it is decoded.
> I'd like to move to a multi-threaded design where each AVCodecContext
> resides in a separate thread with its own AVPacket (concurrent SPSC-)queue
> and the master thread calls av_read_frame() and inserts the coded packet
> into the relevant queue (Actor Model / Erlang style).
> Note that each elementary stream is always decoded by the same single
> thread.
> Before I refactor my code to do this, I'd like to know if there is
> anything on the avlib side *preventing* me from implementing this
> approach.
>    - AVPacket is a pointer to internal and external data. Are there any
>    such data that are shared between elementary streams?
>    - What should I beware of?
> Please advise,
> Thanks,
> Adi
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