[FFmpeg-devel] [PATCH] avformat/aacdec: don't immediately abort if an ADTS frame is not found

[Hendrik Leppkes]

On Mon, Sep 4, 2017 at 4:47 AM, James Almer <jamrial at gmail.com> wrote:
> Skip the invalid data in an attempt to find one instead, and continue decoding from there.
>
> Fixes ticket #6634
>
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavformat/aacdec.c | 41 +++++++++++++++++++++++++++++------------
>  1 file changed, 29 insertions(+), 12 deletions(-)
>
> diff --git a/libavformat/aacdec.c b/libavformat/aacdec.c
> index 364b33404f..7aacc88560 100644
> --- a/libavformat/aacdec.c
> +++ b/libavformat/aacdec.c
> @@ -77,10 +77,29 @@ static int adts_aac_probe(AVProbeData *p)
>          return 0;
>  }
>
> +static int resync(AVFormatContext *s)
> +{
> +    uint16_t state;
> +
> +    state = avio_r8(s->pb);
> +    while (!avio_feof(s->pb) && avio_tell(s->pb) < s->probesize) {
> +        state = (state << 8) | avio_r8(s->pb);
> +        if ((state >> 4) != 0xFFF)
> +            continue;
> +        avio_seek(s->pb, -2, SEEK_CUR);
> +        break;
> +    }
> +

The ADTS sync code isn't that much of a sync code, maybe it might be
more resilient if you try to read the frame size and check if after
that the next frame also starts with a valid code?

- Hendrik