[FFmpeg-devel] [PATCH v5 1/6] avformat/apm: use new extradata format

[Michael Niedermayer]

On Mon, Jul 06, 2020 at 09:24:20AM +0000, Zane van Iperen wrote:
> Signed-off-by: Zane van Iperen <zane at zanevaniperen.com>
> ---
>  libavformat/Makefile |  2 +-
>  libavformat/apm.c    | 62 ++++++++++++++++++++++++--------------------
>  2 files changed, 35 insertions(+), 29 deletions(-)

I think the commit message should be more elaborate
"avformat/apm: use new extradata format"
doesnt really say what changes, why its changes


[...]
> @@ -95,24 +99,29 @@ static int apm_read_header(AVFormatContext *s)
>      int64_t ret;
>      AVStream *st;
>      APMVS12Chunk vs12;
> -    uint8_t buf[APM_VS12_CHUNK_SIZE];
> +    uint8_t buf[APM_FILE_EXTRADATA_SIZE];
>  
>      if (!(st = avformat_new_stream(s, NULL)))
>          return AVERROR(ENOMEM);
>  
> -    /* The header starts with a WAVEFORMATEX */
> -    if ((ret = ff_get_wav_header(s, s->pb, st->codecpar, APM_FILE_HEADER_SIZE, 0)) < 0)
> -        return ret;
> -
> -    if (st->codecpar->bits_per_coded_sample != 4)
> +    /*
> +     * This is 98% a WAVEFORMATEX, but there's something screwy with the extradata
> +     * that ff_get_wav_header() can't (and shouldn't) handle properly.
> +     */
> +    if (avio_rl16(s->pb) != APM_TAG_CODEC)
>          return AVERROR_INVALIDDATA;
>  
> -    if (st->codecpar->codec_tag != APM_TAG_CODEC)
> +    st->codecpar->channels              = avio_rl16(s->pb);
> +    st->codecpar->sample_rate           = avio_rl32(s->pb);

> +    st->codecpar->bit_rate              = avio_rl32(s->pb) * 8;

This can overflow

You also may want to add yourself to the MAINTAINERs file

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Concerning the gods, I have no means of knowing whether they exist or not
or of what sort they may be, because of the obscurity of the subject, and
the brevity of human life -- Protagoras
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