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

Michael Niedermayer michaelni
Mon Oct 25 03:24:18 CEST 2010


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


> 
> 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)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In a rich man's house there is no place to spit but his face.
-- Diogenes of Sinope
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