[FFmpeg-devel] [PATCH] Add a channels field to m4ac

[Baptiste Coudurier]

On 11/10/2009 03:51 PM, Alex Converse wrote:
> As requested for the ALS decoder.
>
>
> m4ac.channels.diff
>
>
> diff --git a/libavcodec/mpeg4audio.c b/libavcodec/mpeg4audio.c
> index 6c0bc7d..8c96572 100644
> --- a/libavcodec/mpeg4audio.c
> +++ b/libavcodec/mpeg4audio.c
> @@ -57,6 +57,8 @@ int ff_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int buf_si
>       c->object_type = get_object_type(&gb);
>       c->sample_rate = get_sample_rate(&gb,&c->sampling_index);
>       c->chan_config = get_bits(&gb, 4);
> +    if (c->chan_config<  FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
> +        c->channels = ff_mpeg4audio_channels[c->chan_config];
>       c->sbr = -1;
>       if (c->object_type == AOT_SBR) {
>           c->ext_object_type = c->object_type;
> diff --git a/libavcodec/mpeg4audio.h b/libavcodec/mpeg4audio.h
> index 98cddad..a51a1a4 100644
> --- a/libavcodec/mpeg4audio.h
> +++ b/libavcodec/mpeg4audio.h
> @@ -36,6 +36,7 @@ typedef struct {
>       int ext_sampling_index;
>       int ext_sample_rate;
>       int ext_chan_config;
> +    int channels;
>   } MPEG4AudioConfig;
>
>   extern const int ff_mpeg4audio_sample_rates[16];
> diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
> index b3b3cc1..5b47f19 100644
> --- a/libavformat/flvdec.c
> +++ b/libavformat/flvdec.c
> @@ -412,7 +412,7 @@ static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)
>                                            st->codec->extradata_size);
>                   if (cfg.chan_config>  7)
>                       return -1;
> -                st->codec->channels = ff_mpeg4audio_channels[cfg.chan_config];
> +                st->codec->channels = cfg.channels;
>                   st->codec->sample_rate = cfg.sample_rate;
>                   dprintf(s, "mp4a config channels %d sample rate %d\n",
>                           st->codec->channels, st->codec->sample_rate);
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 3d67630..65d1aad 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -436,7 +436,7 @@ int ff_mov_read_esds(AVFormatContext *fc, ByteIOContext *pb, MOVAtom atom)
>                                            st->codec->extradata_size);
>                   if (cfg.chan_config>  7)
>                       return -1;
> -                st->codec->channels = ff_mpeg4audio_channels[cfg.chan_config];
> +                st->codec->channels = cfg.channels;
>                   if (cfg.object_type == 29&&  cfg.sampling_index<  3) // old mp3on4
>                       st->codec->sample_rate = ff_mpa_freq_tab[cfg.sampling_index];
>                   else
>

Ok with me.

Btw I think the > 7 check can be dropped in demuxers.
It should be able to demux it even if wronly set, and since it is not 
used anymore to address the array, it should be safe.

-- 
Baptiste COUDURIER
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
FFmpeg maintainer                                  http://www.ffmpeg.org