[FFmpeg-devel] [PATCH 2/2] Add experimental support for Opus in ISO BMFF (MP4)

[James Almer]

On 3/15/2017 10:19 PM, Matthew Gregan wrote:
> Hi,
> 
> The attached patch adds demuxing support for Opus audio codec in
> ISOBMFF/MP4.  This is based on v0.6.8 of the draft spec at
> https://vfrmaniac.fushizen.eu/contents/opus_in_isobmff.html.
> 
> Firefox supports demuxing/playback of these files since Firefox 50.
> 
> 
> 0002-Add-experimental-demuxing-support-for-Opus-in-ISO-BM.patch
> 
> 
> From 9d6f1b4c12b08cf5fbba61bdeb31c785aa1a6a5f Mon Sep 17 00:00:00 2001
> From: Matthew Gregan <kinetik at flim.org>
> Date: Thu, 16 Mar 2017 14:17:21 +1300
> Subject: [PATCH 2/2] Add experimental demuxing support for Opus in ISO BMFF
>  (MP4).
> 
> Based on the draft spec at http://vfrmaniac.fushizen.eu/contents/opus_in_isobmff.html
> 
> Signed-off-by: Matthew Gregan <kinetik at flim.org>
> ---
>  libavformat/mov.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 49 insertions(+)
> 
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index d5c3949050..324d628985 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -5246,6 +5246,54 @@ static int cenc_filter(MOVContext *c, MOVStreamContext *sc, int64_t index, uint8
>      return 0;
>  }
>  
> +static int mov_read_dops(MOVContext *c, AVIOContext *pb, MOVAtom atom)
> +{
> +    const int OPUS_SEEK_PREROLL_MS = 80;
> +    AVStream *st;
> +    size_t size;
> +    int16_t pre_skip;
> +
> +    if (c->fc->nb_streams < 1)
> +        return 0;
> +    st = c->fc->streams[c->fc->nb_streams-1];
> +
> +    if ((uint64_t)atom.size > (1<<30) || atom.size < 11)
> +        return AVERROR_INVALIDDATA;
> +
> +    /* Check OpusSpecificBox version. */
> +    if (avio_r8(pb) != 0) {
> +        av_log(c->fc, AV_LOG_ERROR, "unsupported OpusSpecificBox version\n");
> +        return AVERROR_INVALIDDATA;
> +    }
> +
> +    /* OpusSpecificBox size plus magic for Ogg OpusHead header. */
> +    size = atom.size + 16;

This should be 8. "OpusHead" is not 16 bytes.

> +
> +    if (ff_alloc_extradata(st->codecpar, size))
> +        return AVERROR(ENOMEM);
> +
> +    AV_WL32(st->codecpar->extradata, MKTAG('O','p','u','s'));
> +    AV_WL32(st->codecpar->extradata + 4, MKTAG('H','e','a','d'));
> +    AV_WB8(st->codecpar->extradata + 8, 1); /* OpusHead version */
> +    avio_read(pb, st->codecpar->extradata + 9, size - 17);

Same, this should be size - 9.

> +
> +    /* OpusSpecificBox is stored in big-endian, but OpusHead is
> +       little-endian; aside from the preceeding magic and version they're
> +       otherwise currently identical.  Data after output gain at offset 16
> +       doesn't need to be bytewapped. */
> +    pre_skip = AV_RB16(st->codecpar->extradata + 10);
> +    AV_WL16(st->codecpar->extradata + 10, pre_skip);
> +    AV_WL32(st->codecpar->extradata + 12, AV_RB32(st->codecpar->extradata + 12));
> +    AV_WL16(st->codecpar->extradata + 16, AV_RB16(st->codecpar->extradata + 16));
> +
> +    st->codecpar->initial_padding = pre_skip;
> +    st->codecpar->seek_preroll = av_rescale_q(OPUS_SEEK_PREROLL_MS,
> +                                              (AVRational){1, 1000},
> +                                              (AVRational){1, 48000});
> +
> +    return 0;
> +}
> +
>  static const MOVParseTableEntry mov_default_parse_table[] = {
>  { MKTAG('A','C','L','R'), mov_read_aclr },
>  { MKTAG('A','P','R','G'), mov_read_avid },
> @@ -5327,6 +5375,7 @@ static const MOVParseTableEntry mov_default_parse_table[] = {
>  { MKTAG('d','f','L','a'), mov_read_dfla },
>  { MKTAG('s','t','3','d'), mov_read_st3d }, /* stereoscopic 3D video box */
>  { MKTAG('s','v','3','d'), mov_read_sv3d }, /* spherical video box */
> +{ MKTAG('d','O','p','s'), mov_read_dops },
>  { 0, NULL }
>  };
>  
> -- 2.12.0
> 
> 
> 
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