[FFmpeg-devel] [PATCH] fftools/ffmpeg_dec: abort if avcodec_send_packet() returns EAGAIN

[James Almer]

On 5/24/2023 8:31 AM, James Almer wrote:
> As the comment in the code mentions, EAGAIN is not an expected value here
> because we call avcodec_receive_frame() until all frames have been returned.
> avcodec_send_packet() returning EAGAIN means a packet is still buffered, which
> hints that the underlying decoder is buggy and not fetching packets as it
> should.
> 
> An example of this behavior was in the libdav1d wrapper before f209614290,
> where feeding it split frames (or individual OBUs) would result in the CLI
> eventually printing the unuseful "Error submitting packet to decoder: Resource
> temporarily unavailable" error message, and just keep until EOF without
> returning new frames.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> Now compiling.
> 
>   fftools/ffmpeg_dec.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/fftools/ffmpeg_dec.c b/fftools/ffmpeg_dec.c
> index e06747d9c4..b1db9b30d0 100644
> --- a/fftools/ffmpeg_dec.c
> +++ b/fftools/ffmpeg_dec.c
> @@ -390,6 +390,11 @@ int dec_packet(InputStream *ist, const AVPacket *pkt, int no_eof)
>       if (ret < 0 && !(ret == AVERROR_EOF && !pkt)) {
>           // In particular, we don't expect AVERROR(EAGAIN), because we read all
>           // decoded frames with avcodec_receive_frame() until done.
> +        if (ret == AVERROR(EAGAIN)) {
> +            av_log(ist, AV_LOG_FATAL, "A decoder returned an unexpected error code. "
> +                   "This is a bug, please report it.\n");
> +            exit_program(1);
> +        }
>           av_log(ist, AV_LOG_ERROR, "Error submitting %s to decoder: %s\n",
>                  pkt ? "packet" : "EOF", av_err2str(ret));
>           if (exit_on_error)

Will apply.