Re: [FFmpeg-devel] [PATCH v2 2/4] avcodec/mlpdec: add detection of Atmos spatial extension profile in TrueHD

[Hendrik Leppkes <h.leppkes@gmail.com>]

On Sat, Feb 18, 2023 at 2:15 AM Marth64 <marth64@proxyid.net> wrote:
>
> Signed-off-by: Marth64 <marth64@proxyid.net>
> ---
>  libavcodec/avcodec.h    |  2 ++
>  libavcodec/codec_desc.c |  1 +
>  libavcodec/mlpdec.c     | 11 +++++++++++
>  libavcodec/profiles.c   |  5 +++++
>  libavcodec/profiles.h   |  1 +
>  5 files changed, 20 insertions(+)
>
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 0e85dd50a4..3feab75741 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -1593,6 +1593,8 @@ typedef struct AVCodecContext {
>
>  #define FF_PROFILE_EAC3_DDP_ATMOS         30
>
> +#define FF_PROFILE_TRUEHD_ATMOS           30
> +
>  #define FF_PROFILE_MPEG2_422    0
>  #define FF_PROFILE_MPEG2_HIGH   1
>  #define FF_PROFILE_MPEG2_SS     2
> diff --git a/libavcodec/codec_desc.c b/libavcodec/codec_desc.c
> index 4098d4f5a5..e80ac07700 100644
> --- a/libavcodec/codec_desc.c
> +++ b/libavcodec/codec_desc.c
> @@ -2960,6 +2960,7 @@ static const AVCodecDescriptor codec_descriptors[] = {
>          .name      = "truehd",
>          .long_name = NULL_IF_CONFIG_SMALL("TrueHD"),
>          .props     = AV_CODEC_PROP_LOSSLESS,
> +        .profiles  = NULL_IF_CONFIG_SMALL(ff_truehd_profiles),
>      },
>      {
>          .id        = AV_CODEC_ID_MP4ALS,
> diff --git a/libavcodec/mlpdec.c b/libavcodec/mlpdec.c
> index 0ee1f0982c..85d6207b9c 100644
> --- a/libavcodec/mlpdec.c
> +++ b/libavcodec/mlpdec.c
> @@ -42,6 +42,7 @@
>  #include "mlpdsp.h"
>  #include "mlp.h"
>  #include "config.h"
> +#include "profiles.h"
>
>  /** number of bits used for VLC lookup - longest Huffman code is 9 */
>  #if ARCH_ARM
> @@ -392,6 +393,15 @@ static int read_major_sync(MLPDecodeContext *m, GetBitContext *gb)
>      m->num_substreams        = mh.num_substreams;
>      m->substream_info        = mh.substream_info;
>
> +    /*  If there is a 4th substream and the MSB of substream_info is set,
> +     *  there is a 16-channel spatial presentation (Atmos in TrueHD).
> +     */
> +    if (m->avctx->codec_id == AV_CODEC_ID_TRUEHD
> +            && m->num_substreams == 4
> +            && m->substream_info >> 7 == 1) {
> +        m->avctx->profile     = FF_PROFILE_TRUEHD_ATMOS;
> +    }
> +

Nit: maybe put the if into two lines instead of three? The two
substream checks look like they should fit in one line quite well. But
this is just a style question, so feel free to ignore.

Otherwise LGTM
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