[FFmpeg-devel] [PATCH 3/3] avcodec/mpeg4video: Detect reference studio streams as studio streams

[Michael Niedermayer]

On Sun, Apr 29, 2018 at 11:21:58PM +0000, Kieran Kunhya wrote:
> On Sun, 29 Apr 2018 at 22:57 Michael Niedermayer <michael at niedermayer.cc>
> wrote:
> 
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >  libavcodec/mpeg4video.h    |  2 ++
> >  libavcodec/mpeg4videodec.c | 25 ++++++++++++++++---------
> >  2 files changed, 18 insertions(+), 9 deletions(-)
> >
> > diff --git a/libavcodec/mpeg4video.h b/libavcodec/mpeg4video.h
> > index f974792887..dd0a59038d 100644
> > --- a/libavcodec/mpeg4video.h
> > +++ b/libavcodec/mpeg4video.h
> > @@ -41,6 +41,8 @@
> >  #define NBIT_VO_TYPE             5
> >  #define ARTS_VO_TYPE            10
> >  #define ACE_VO_TYPE             12
> > +#define SIMPLE_STUDIO_VO_TYPE   14
> > +#define CORE_STUDIO_VO_TYPE     15
> >  #define ADV_SIMPLE_VO_TYPE      17
> >
> >  #define VOT_VIDEO_ID 1
> > diff --git a/libavcodec/mpeg4videodec.c b/libavcodec/mpeg4videodec.c
> > index ada5cdc6fa..d2b5e90331 100644
> > --- a/libavcodec/mpeg4videodec.c
> > +++ b/libavcodec/mpeg4videodec.c
> > @@ -46,6 +46,8 @@
> >  #define MB_TYPE_B_VLC_BITS 4
> >  #define STUDIO_INTRA_BITS 9
> >
> > +static int decode_studio_vol_header(Mpeg4DecContext *ctx, GetBitContext
> > *gb);
> > +
> >  static VLC dc_lum, dc_chrom;
> >  static VLC sprite_trajectory;
> >  static VLC mb_type_b_vlc;
> > @@ -2049,6 +2051,18 @@ static int decode_vol_header(Mpeg4DecContext *ctx,
> > GetBitContext *gb)
> >      /* vol header */
> >      skip_bits(gb, 1);                   /* random access */
> >      s->vo_type = get_bits(gb, 8);
> > +
> > +    if (s->vo_type == CORE_STUDIO_VO_TYPE ||
> > +        s->vo_type == SIMPLE_STUDIO_VO_TYPE) {
> > +        if (s->avctx->profile != FF_PROFILE_UNKNOWN && s->avctx->profile
> > != FF_PROFILE_MPEG4_SIMPLE_STUDIO)
> > +            return AVERROR_INVALIDDATA;
> > +        s->studio_profile = 1;
> > +        s->avctx->profile = FF_PROFILE_MPEG4_SIMPLE_STUDIO;
> > +        return decode_studio_vol_header(ctx, gb);
> > +    } else if (s->studio_profile) {
> > +        return AVERROR_PATCHWELCOME;
> > +    }
> > +
> >      if (get_bits1(gb) != 0) {           /* is_ol_id */
> >          vo_ver_id = get_bits(gb, 4);    /* vo_ver_id */
> >          skip_bits(gb, 3);               /* vo_priority */
> > @@ -3001,8 +3015,6 @@ static int decode_studio_vol_header(Mpeg4DecContext
> > *ctx, GetBitContext *gb)
> >      int width, height;
> >      int bits_per_raw_sample;
> >
> > -            skip_bits1(gb); /* random_accessible_vol */
> > -            skip_bits(gb, 8); /* video_object_type_indication */
> >              skip_bits(gb, 4); /* video_object_layer_verid */
> >
> 
> Please add a comment explaining what you've done here, someone might look
> at this code in 10 years time (exactly like I did) and not understand why
> you are mixing normal vol header and studio vol header.

yes, this is a good idea
Ill add some comments and apply

thx


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20180516/50eee7fa/attachment.sig>