[FFmpeg-devel] [PATCH 1/2] allow passing subtitles header between decoder and encoder

Aurelien Jacobs aurel
Sun Nov 7 23:44:03 CET 2010


On Mon, Oct 25, 2010 at 03:24:18AM +0200, Michael Niedermayer wrote:
> On Mon, Oct 25, 2010 at 12:04:59AM +0200, Aurelien Jacobs wrote:
> > On Sat, Oct 23, 2010 at 09:57:26PM +0200, Michael Niedermayer wrote:
> > > On Tue, Oct 19, 2010 at 09:55:47PM +0200, Aurelien Jacobs wrote:
> > > > On Tue, Oct 19, 2010 at 03:43:52PM +0200, Michael Niedermayer wrote:
> > > > > On Sat, Oct 16, 2010 at 05:31:26PM +0200, Aurelien Jacobs wrote:
> > > > > > ---
> > > > > >  ffmpeg.c             |   11 +++++++++++
> > > > > >  libavcodec/avcodec.h |    8 ++++++++
> > > > > >  libavcodec/utils.c   |    2 ++
> > > > > >  libavformat/utils.c  |    4 ++++
> > > > > >  4 files changed, 25 insertions(+), 0 deletions(-)
> > > > > > 
> > > > > > diff --git a/ffmpeg.c b/ffmpeg.c
> > > > > > index 4f59b2e..7622ccc 100644
> > > > > > --- a/ffmpeg.c
> > > > > > +++ b/ffmpeg.c
> > > > > > @@ -2365,6 +2365,7 @@ static int transcode(AVFormatContext **output_files,
> > > > > >          ost = ost_table[i];
> > > > > >          if (ost->encoding_needed) {
> > > > > >              AVCodec *codec = i < nb_output_codecs ? output_codecs[i] : NULL;
> > > > > > +            AVCodecContext *dec = ist_table[ost->source_index]->st->codec;
> > > > > >              if (!codec)
> > > > > >                  codec = avcodec_find_encoder(ost->st->codec->codec_id);
> > > > > >              if (!codec) {
> > > > > > @@ -2373,6 +2374,15 @@ static int transcode(AVFormatContext **output_files,
> > > > > >                  ret = AVERROR(EINVAL);
> > > > > >                  goto dump_format;
> > > > > >              }
> > > > > > +            if (dec->subtitle_header) {
> > > > > > +                ost->st->codec->subtitle_header = av_malloc(dec->subtitle_header_size);
> > > > > > +                if (!ost->st->codec->subtitle_header) {
> > > > > > +                    ret = AVERROR(ENOMEM);
> > > > > > +                    goto dump_format;
> > > > > > +                }
> > > > > > +                memcpy(ost->st->codec->subtitle_header, dec->subtitle_header, dec->subtitle_header_size);
> > > > > > +                ost->st->codec->subtitle_header_size = dec->subtitle_header_size;
> > > > > > +            }
> > > > > >              if (avcodec_open(ost->st->codec, codec) < 0) {
> > > > > >                  snprintf(error, sizeof(error), "Error while opening encoder for output stream #%d.%d - maybe incorrect parameters such as bit_rate, rate, width or height",
> > > > > >                          ost->file_index, ost->index);
> > > > > > @@ -2728,6 +2738,7 @@ static int transcode(AVFormatContext **output_files,
> > > > > >                  }
> > > > > >                  av_fifo_free(ost->fifo); /* works even if fifo is not
> > > > > >                                               initialized but set to zero */
> > > > > > +                av_freep(&ost->st->codec->subtitle_header);
> > > > > >                  av_free(ost->pict_tmp.data[0]);
> > > > > >                  if (ost->video_resample)
> > > > > >                      sws_freeContext(ost->img_resample_ctx);
> > > > > > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > > > > > index 4bddbaa..ab3cbd9 100644
> > > > > > --- a/libavcodec/avcodec.h
> > > > > > +++ b/libavcodec/avcodec.h
> > > > > > @@ -2744,6 +2744,14 @@ typedef struct AVCodecContext {
> > > > > >       * - decoding: unused
> > > > > >       */
> > > > > >      int lpc_passes;
> > > > > > +
> > > > > > +    /**
> > > > > > +     * Header containing style information for text subtitles.
> > > > > > +     * - encoding: Set/allocated/freed by user (before avcodec_open())
> > > > > > +     * - decoding: Set/allocated/freed by libavcodec (by avcodec_open())
> > > > > > +     */
> > > > > > +    uint8_t *subtitle_header;
> > > > > > +    int subtitle_header_size;
> > > > > >  } AVCodecContext;
> > > > > >  
> > > > > >  /**
> > > > > 
> > > > > The description should be enough to implement a decoder and a user app and
> > > > > a subtitle renderer based on it. (some common sense and guessing not excluded)
> > > > > but this seems too terse for that
> > > > 
> > > > OK. Updated patch.
> > > > I think it should now be enough to implement anything related to this
> > > > field, with a little bit of common sense and the ASS spec around.
> > > > 
> > > > > also are you sure every subtitle decoder will be able to set this by
> > > > > avcodec_open() ?
> > > > 
> > > > Yes, sure. It wouldn't be very useful anyway to set it later on.
> > > > I've already (started to) implement several decoders (SubRip,
> > > > MicroDVD, Movtext...), and they fits well within this model.
> > > > 
> > > > Aurel
> > > > 
> > > > [...]
> > > > 
> > > > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > > > index 4bddbaa..99bc7ad 100644
> > > > --- a/libavcodec/avcodec.h
> > > > +++ b/libavcodec/avcodec.h
> > > > @@ -2744,6 +2744,17 @@ typedef struct AVCodecContext {
> > > >       * - decoding: unused
> > > >       */
> > > >      int lpc_passes;
> > > > +
> > > > +    /**
> > > > +     * Header containing style information for text subtitles.
> > > > +     * For SUBTITLE_ASS subtitle type, it should contain the whole ASS
> > > > +     * [Script Info] and [V4+ Styles] section, plus the [Events] line and
> > > > +     * the Format line following. It shouldn't include any Dialogue line.
> > > 
> > > 
> > > 
> > > > +     * - encoding: Set/allocated/freed by user (before avcodec_open())
> > > [...]
> > > > @@ -742,6 +742,8 @@ av_cold int avcodec_close(AVCodecContext *avctx)
> > > >      av_freep(&avctx->priv_data);
> > > >      if(avctx->codec && avctx->codec->encode)
> > > >          av_freep(&avctx->extradata);
> > > > +    if (avctx->codec && avctx->codec->encode)
> > > > +        av_freep(&avctx->subtitle_header);
> > > >      avctx->codec = NULL;
> > > >      entangled_thread_counter--;
> > > 
> > > doesnt match
> > 
> > Right !
> > To be consistent it seems better to let the application free the memory
> > it allocated, so I just removed this av_freep(). Anyway, there was
> > already the needed av_freep() in ffmpeg.
> > 
> > > > diff --git a/libavformat/utils.c b/libavformat/utils.c
> > > > index 8a08557..a137e69 100644
> > > > --- a/libavformat/utils.c
> > > > +++ b/libavformat/utils.c
> > > > @@ -2022,6 +2022,9 @@ static int has_codec_parameters(AVCodecContext *enc)
> > > >      case AVMEDIA_TYPE_VIDEO:
> > > >          val = enc->width && enc->pix_fmt != PIX_FMT_NONE;
> > > >          break;
> > > > +    case AVMEDIA_TYPE_SUBTITLE:
> > > > +        val = !!enc->subtitle_header;
> > > > +        break;
> > > >      default:
> > > >          val = 1;
> > > >          break;
> > > 
> > > This will slow every sub title decoder down that never sets this
> > 
> > The best way to fix this is probably to add a new capability flag to
> > codecs which use a subtitle_header, and check for this flag here.
> > Is this OK ?
> 
> if subtitle_header is part of the format then its the format (text/ass/bitmap)
> that decides if such header should be expected.

Kind of...

> But if that doesnt work out then a flag could be used too

Indeed, that doesn't work out. The format (text/ass/bitmap) is a
property of the resulting AVSubtitle, not of the AVCodec.
libavformat need this information before opening the codec, so
a flag in AVCodec seems the best solution to me.

> > Aurel
> >  ffmpeg.c             |   11 +++++++++++
> >  libavcodec/avcodec.h |   15 +++++++++++++++
> >  libavformat/utils.c  |    8 ++++++++
> >  3 files changed, 34 insertions(+)
> > 708fe8c4e44e8f2d2252805a53b8a7633e202579  subtitle_header.diff
> > commit 078a2c04c0970178c729e3cabed3ae7c5d8cb7fa
> > Author: Aurelien Jacobs <aurel at gnuage.org>
> > Date:   Thu Aug 5 22:12:37 2010 +0200
> > 
> >     allow passing subtitles header between decoder and encoder
> > 
> > diff --git a/ffmpeg.c b/ffmpeg.c
> > index 4f59b2e..7622ccc 100644
> > --- a/ffmpeg.c
> > +++ b/ffmpeg.c
> > @@ -2365,6 +2365,7 @@ static int transcode(AVFormatContext **output_files,
> >          ost = ost_table[i];
> >          if (ost->encoding_needed) {
> >              AVCodec *codec = i < nb_output_codecs ? output_codecs[i] : NULL;
> > +            AVCodecContext *dec = ist_table[ost->source_index]->st->codec;
> >              if (!codec)
> >                  codec = avcodec_find_encoder(ost->st->codec->codec_id);
> >              if (!codec) {
> > @@ -2373,6 +2374,15 @@ static int transcode(AVFormatContext **output_files,
> >                  ret = AVERROR(EINVAL);
> >                  goto dump_format;
> >              }
> > +            if (dec->subtitle_header) {
> > +                ost->st->codec->subtitle_header = av_malloc(dec->subtitle_header_size);
> > +                if (!ost->st->codec->subtitle_header) {
> > +                    ret = AVERROR(ENOMEM);
> > +                    goto dump_format;
> > +                }
> > +                memcpy(ost->st->codec->subtitle_header, dec->subtitle_header, dec->subtitle_header_size);
> > +                ost->st->codec->subtitle_header_size = dec->subtitle_header_size;
> > +            }
> >              if (avcodec_open(ost->st->codec, codec) < 0) {
> >                  snprintf(error, sizeof(error), "Error while opening encoder for output stream #%d.%d - maybe incorrect parameters such as bit_rate, rate, width or height",
> >                          ost->file_index, ost->index);
> > @@ -2728,6 +2738,7 @@ static int transcode(AVFormatContext **output_files,
> >                  }
> >                  av_fifo_free(ost->fifo); /* works even if fifo is not
> >                                               initialized but set to zero */
> > +                av_freep(&ost->st->codec->subtitle_header);
> >                  av_free(ost->pict_tmp.data[0]);
> >                  if (ost->video_resample)
> >                      sws_freeContext(ost->img_resample_ctx);
> > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> > index 4bddbaa..af9523b 100644
> > --- a/libavcodec/avcodec.h
> > +++ b/libavcodec/avcodec.h
> > @@ -707,6 +707,10 @@ typedef struct RcOverride{
> >   * Codec should fill in channel configuration and samplerate instead of container
> >   */
> >  #define CODEC_CAP_CHANNEL_CONF     0x0400
> > +/**
> > + * Codec is making use of subtitle_header
> > + */
> > +#define CODEC_CAP_SUBTITLE_HEADER  0x0800
> >  
> >  
> >  //The following defines may change, don't expect compatibility if you use them.
> > @@ -2744,6 +2748,17 @@ typedef struct AVCodecContext {
> >       * - decoding: unused
> >       */
> >      int lpc_passes;
> > +
> > +    /**
> > +     * Header containing style information for text subtitles.
> > +     * For SUBTITLE_ASS subtitle type, it should contain the whole ASS
> > +     * [Script Info] and [V4+ Styles] section, plus the [Events] line and
> > +     * the Format line following. It shouldn't include any Dialogue line.
> > +     * - encoding: Set/allocated/freed by user (before avcodec_open())
> > +     * - decoding: Set/allocated/freed by libavcodec (by avcodec_open())
> > +     */
> > +    uint8_t *subtitle_header;
> > +    int subtitle_header_size;
> >  } AVCodecContext;
> >  
> >  /**
> > diff --git a/libavformat/utils.c b/libavformat/utils.c
> > index 8a08557..043e251 100644
> > --- a/libavformat/utils.c
> > +++ b/libavformat/utils.c
> > @@ -2006,6 +2006,7 @@ static void av_estimate_timings(AVFormatContext *ic, int64_t old_offset)
> >  
> >  static int has_codec_parameters(AVCodecContext *enc)
> >  {
> > +    AVCodec *codec = enc->codec;
> >      int val;
> >      switch(enc->codec_type) {
> >      case AVMEDIA_TYPE_AUDIO:
> > @@ -2022,6 +2023,12 @@ static int has_codec_parameters(AVCodecContext *enc)
> >      case AVMEDIA_TYPE_VIDEO:
> >          val = enc->width && enc->pix_fmt != PIX_FMT_NONE;
> >          break;
> > +    case AVMEDIA_TYPE_SUBTITLE:
> > +        if (!codec)
> 
> > +            codec = avcodec_find_decoder(enc->codec_id);
> 
> that is ugly (and slow)

OK. I droped it and added an AVCodec parameter to the
has_codec_parameters() funtion instead.

Aurel
-------------- next part --------------
A non-text attachment was scrubbed...
Name: subtitle_header.diff
Type: text/x-diff
Size: 6803 bytes
Desc: not available
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20101107/4672e7fa/attachment.diff>



More information about the ffmpeg-devel mailing list