On Sun, 2 Aug 2020 14:14:45 +0200
"Andreas Rheinhardt" <andreas.rheinha...@gmail.com> wrote:
>
> Zane van Iperen:
> >>> +static int argo_asf_write_trailer(AVFormatContext *s)
> >>> +{
> >>> + int64_t data_size, num_blocks;
> >>> +
> >>> + data_size = avio_tell(s->pb) - (ASF_FILE_HEADER_SIZE +
> >>> ASF_CHUNK_HEADER_SIZE);
> >>> + num_blocks = data_size / (17 * s->streams[0]->codecpar->channels);
> >>> +
> >>> + av_assert0(data_size % (17 * s->streams[0]->codecpar->channels) ==
> >>> 0);
> >>
> >> You must not assert this as you have not have any check in place that
> >> guarantees this.
> >>
> >> The comment in the demuxer and the value you assign to num_samples when
> >> writing the header indicates to me that num_samples is supposed to be
> >> always 32; yet there is no check for that in the demuxer and if it is a
> >> value different from 32 and 33, then simply remuxing such a file can
> >> trigger this assert.
> >>
> >
> > You're right, num_samples should always be 32. I will add a check in
> > the demuxer.
> >
> > The 17 comes from "control byte + (32 / 2)" (the frame size for a
> > single channel), so adding that check should guarantee the assertion.
> >
>
> Why? The packets sent to this muxer need not originate from the demuxer
> via remuxing or from the encoder that you are about to add.
So, something like this basically:
static int argo_asf_write_packet(AVFormatContext *s, AVPacket *pkt)
{
if (pkt->size != 17 && pkt->size != 34)
return AVERROR(EINVAL);
avio_write(s->pb, pkt->data, pkt->size);
return 0;
}
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