[FFmpeg-devel] [PATCH] avformat: Allow forcing use of AVParsers

[Paul B Mahol]

On 9/5/16, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> Hi,
>
> On Sep 5, 2016 12:05 PM, "Michael Niedermayer" <michael at niedermayer.cc>
> wrote:
>>
>> On Mon, Sep 05, 2016 at 05:25:14AM -0400, Ronald S. Bultje wrote:
>> > Hi,
>> >
>> > On Sep 5, 2016 11:18 AM, "Michael Niedermayer" <michael at niedermayer.cc>
>> > wrote:
>> > >
>> > > TODO: version bump, docs
>> > >
>> > > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
>> > > ---
>> > >  libavformat/avformat.h      | 8 ++++++++
>> > >  libavformat/options_table.h | 1 +
>> > >  libavformat/utils.c         | 3 +++
>> > >  3 files changed, 12 insertions(+)
>> > >
>> > > diff --git a/libavformat/avformat.h b/libavformat/avformat.h
>> > > index 3ee7051..33b921a 100644
>> > > --- a/libavformat/avformat.h
>> > > +++ b/libavformat/avformat.h
>> > > @@ -1886,6 +1886,14 @@ typedef struct AVFormatContext {
>> > >       * - decoding: set by user through AVOptions (NO direct access)
>> > >       */
>> > >      char *protocol_blacklist;
>> > > +
>> > > +    /**
>> > > +     * Force parsing.
>> > > +     * - encoding: unused
>> > > +     * - decoding: set by user through AVOptions (NO direct access)
>> > > +     */
>> > > +    int force_parsing;
>> > > +
>> > >  } AVFormatContext;
>> > >
>> > >  int av_format_get_probe_score(const AVFormatContext *s);
>> > > diff --git a/libavformat/options_table.h b/libavformat/options_table.h
>> > > index 3b74d1b..359796c 100644
>> > > --- a/libavformat/options_table.h
>> > > +++ b/libavformat/options_table.h
>> > > @@ -103,6 +103,7 @@ static const AVOption avformat_options[] = {
>> > >  {"format_whitelist", "List of demuxers that are allowed to be used",
>> > OFFSET(format_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },
>  CHAR_MIN,
>> > CHAR_MAX, D },
>> > >  {"protocol_whitelist", "List of protocols that are allowed to be
> used",
>> > OFFSET(protocol_whitelist), AV_OPT_TYPE_STRING, { .str = NULL },
>  CHAR_MIN,
>> > CHAR_MAX, D },
>> > >  {"protocol_blacklist", "List of protocols that are not allowed to be
>> > used", OFFSET(protocol_blacklist), AV_OPT_TYPE_STRING, { .str = NULL },
>> > CHAR_MIN, CHAR_MAX, D },
>> > > +{"forceparsing", "force use of AVParsers", OFFSET(force_parsing),
>> > AV_OPT_TYPE_INT, { .i64 = -1 },  -1, AVSTREAM_PARSE_FULL_ONCE, D },
>> > >  {NULL},
>> > >  };
>> >
>> > Why int?
>>
>> what else ?
>> a flag doesnt work as AVStreamParseType has more than 1 value
>
> An enum would be nice.
>
>> > At vdd, we discussed parsers, maybe we should sync on that because I
>> > believe it makes this unnecessary.
>>
>> not sure i understand what you suggest ?
>
> Anton expressed interest in merging parsers and bitstream filters. I
> believe they are (other than semantically) identical in goal, and the
> semantic difference is sometimes violated already. If you think of them as
> bitstream filters, we could merge their functionality with auto-insertion
> of BSF. It was proposed that we could go one step further and do parsing
> not in the demuxer step (av_read_frame), but before the decoder (which is a
> change) and in the muxer (which we already do). Auto-insertion mechanisms
> would be shared and this would lead to interesting new features that
> someone demuxing a mpeg system stream or vp9/divx-with-packed-b-frames
> using external tools (which don't split/reframe) but using avcodec decoders
> would still see it work. On the other hand, people using lavf to demux such
> streams would not need to merge (divx/vp9) before muxing, making that
> process more efficient (using lavf) or less buggy (using non-lavf muxers).

Are you telling that using non-lavf muxers is less buggy?