[Libav-user] Using libavformat/libavcodec with sample accurate seeking

[Christopher Snowhill]

On 8/28/16 12:50 AM, Paul B Mahol wrote:
> Hi,
>
> On Sun, Aug 28, 2016 at 7:16 AM, Christopher Snowhill
> <kode54 at gmail.com <mailto:kode54 at gmail.com>> wrote:
>
>     I've noticed that when using these libraries in my own projects, at
>     least in VGMStream, and with the WMA Pro codec, it is necessary to
>     perform my own pre-roll when seeking for looping, or else the codec
>     ramps the audio in from silence on every loop as it catches back
>     up to a
>     valid state. I currently use either two seconds, or the beginning
>     of the
>     file if it's less than two seconds prior to the intended seek point,
>     then discard sample data that is returned by the decoder.
>
>     Is this always necessary by design? Or am I misusing the seeking API?
>
>     I currently use:
>
>     int64_t ts = target_sample * formatCtx->duration / total_samples;
>     avformat_seek_file(formatCtx, -1, ts - 1000, ts, ts, AVSEEK_FLAG_ANY);
>
>
> Do you call avcodec_flush_buffers()?
Yes, I do. Immediately after avformat_seek_file.
>
>
>
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