[Libav-user] decoder never starts

[Ben Harper]

You say that the stream is "only P frames". I thought that one needs I
frames to start the decode?

Also, have you tried sending the SPS/PPS as the very first packets to
decode,
before sending any visual packets? I've found this is necessary when
encoding
to file formats such as mp4, so it might be necessary for decode too.


On Mon, Feb 12, 2024 at 5:34 PM David Ibbitson <david.ibbitson at gmail.com>
wrote:

> Hi folks,
>
> I have an mpegts file with the following stream:
>
> Input #0, mpegts, from 'Downloads/e318_save.ts':
>   Duration: 00:03:59.00, start: 8.400000, bitrate: 137 kb/s
>   Program 1
>     Metadata:
>       service_name    : Service01
>       service_provider: FFmpeg
>   Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B),
> yuv420p(progressive), 640x480, 5 fps, 5 tbr, 90k tbn, 10 tbc
>
> It's only P frames with the occasional SPS/PPS. The ffmpeg tools handle it
> fine.
>
> However when I demux the h264 and invoke the standard
> avcodec_send_packet/avcodec_receive_frame loops nothing happens.
>
> avcodec_send_packet just continues to accept data (never hits an
> erors condition) and avcodec_receive_frame immediately hits EAGAIN.
>
> Any ideas what could be happening here?
>
> Thanks,
> David
>
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