[FFmpeg-devel] [PATCH] avformat/bit: return early from write_packet if pkt->size is 0

[Andreas Cadhalpun]

On 26.02.2015 20:48, Nicolas George wrote:
> L'octidi 8 ventôse, an CCXXIII, Andreas Cadhalpun a écrit :
>> the bit format muxer currently segfaults, when it is passed a packet of size 0.
>> This can be triggered e.g. with:
>> ffmpeg -y -f lavfi -i sine=duration=0.1 -c:a flac -f bit /dev/null
>>
>> Attached patch fixes this.
>
> This looks wrong. The "bit" muxer seems to assume packets have a constant
> size, apparently 10 octets. Someone knowing the format should check, but I
> suppose this would be more correct:
>
>          if (pkt->size != 10)
>              return AVERROR(EINVAL);

You're right. New patch with this check attached.

> Also, it seems you should not be able to mux FLAC into this format, the
> write header callback does not validate enough. It looks like this muxer is
> a quick-and-dirty implementation, emphasis on the dirty.

Indeed. I also attached a patch limiting the bit muxer to codec g729 with 1 
channel, as this is apparently the only thing it supports.

> Last: how come ffmpeg/lavf tries to mux an empty packet?

You already analyzed this.

Best regards,
Andreas

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