[Libav-user] Parse raw movie packet data into AVPacket

[Matthew Einhorn]

On Tue, Nov 8, 2011 at 5:36 AM, dream01 at email.it <dream01 at email.it> wrote:
> Matthew Einhorn <moiein2000 at ...> writes:
>
>> Have you looked into using custom IO calls like here:
>> http://cdry.wordpress.com/2009/09/09/using-custom-io-callbacks-with-ffmpeg/
>
> Thank you very much! It's exactly what I need.
> But it works only partially, I mean, I'm able to play the movie file directly
> from the buffer but I am not able to seek.
>
> I've implemented the seek function but it doesn't work as expected.
> As I seek, the seek callback function is correctly called with
> SEEK_SET as whence but it behaves in a strange way.
>
> I try to explain this clearly:
>
> seek function is called with the required file position to seek to,
> then I seek into my buffer to reach the
> required position and return the new position after seek.
> Remember that my buffer is an exact 1:1 copy byte by byte of
> the entire file, so seeking to a certain position in a file is
> equal to seeking to that position in my buffer.
>
> After seek callback function has returned, it gets called
> once again with SEEK_SET as whence and with a negative offset,
> therefore I am supposed to seek to a negative position in
> my file/buffer.
> This obviously makes seek function to return -1 and therefore
> also av_seek_frame returns -1 and this is interpreted as end-of-file.
>
> Where is the mistake?
> I don't know if this is important or not, but my buffer is a copy of
> a m2ts file which contains:
> video (h264), audio (DTS and AC3) and subtitles (PGS).
>

I haven't personally used the custom IO interface so I don't know why
you're having trouble, but I believe there's a flag called seekable
which you can set to 0 if you don't need seeking, but that won't fix
seeking.