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[FFmpeg-devel,2/4] avformat/ttmlenc: enable writing out additional header values

Message ID 20210330082346.8404-3-jeebjp@gmail.com
State New
Headers show
Series Initial region (styling) support for TTML
Related show

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Commit Message

Jan Ekström March 30, 2021, 8:23 a.m. UTC
From: Jan Ekström <jan.ekstrom@24i.com>

This way the encoder may pass on the following values to the muxer:
1) Additional root "tt" element attributes, such as the subtitle
   canvas reference size.
2) Anything before the body element of the document, such as regions
   in the head element, which can configure styles.

Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
---
 libavcodec/ttmlenc.h  |  5 +++
 libavformat/ttmlenc.c | 78 ++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 78 insertions(+), 5 deletions(-)

Comments

Andreas Rheinhardt March 30, 2021, 9:18 a.m. UTC | #1
Jan Ekström:
> From: Jan Ekström <jan.ekstrom@24i.com>
> 
> This way the encoder may pass on the following values to the muxer:
> 1) Additional root "tt" element attributes, such as the subtitle
>    canvas reference size.
> 2) Anything before the body element of the document, such as regions
>    in the head element, which can configure styles.
> 
> Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
> ---
>  libavcodec/ttmlenc.h  |  5 +++
>  libavformat/ttmlenc.c | 78 ++++++++++++++++++++++++++++++++++++++++---
>  2 files changed, 78 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/ttmlenc.h b/libavcodec/ttmlenc.h
> index c1dd5ec990..c3bb11478d 100644
> --- a/libavcodec/ttmlenc.h
> +++ b/libavcodec/ttmlenc.h
> @@ -25,4 +25,9 @@
>  #define TTMLENC_EXTRADATA_SIGNATURE "lavc-ttmlenc"
>  #define TTMLENC_EXTRADATA_SIGNATURE_SIZE (sizeof(TTMLENC_EXTRADATA_SIGNATURE) - 1)
>  
> +static const char ttml_default_namespacing[] =
> +"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
> +"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
> +"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n";
> +
>  #endif /* AVCODEC_TTMLENC_H */
> diff --git a/libavformat/ttmlenc.c b/libavformat/ttmlenc.c
> index 940f8bbd4e..5d9ad6b756 100644
> --- a/libavformat/ttmlenc.c
> +++ b/libavformat/ttmlenc.c
> @@ -37,18 +37,23 @@ enum TTMLPacketType {
>      PACKET_TYPE_DOCUMENT,
>  };
>  
> +struct TTMLHeaderParameters {
> +    char *tt_element_params;
> +    char *pre_body_elements;
> +};
> +
>  typedef struct TTMLMuxContext {
>      enum TTMLPacketType input_type;
>      unsigned int document_written;
> +    struct TTMLHeaderParameters header_params;
>  } TTMLMuxContext;
>  
>  static const char ttml_header_text[] =
>  "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
>  "<tt\n"
> -"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
> -"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
> -"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n"
> +"%s"
>  "  xml:lang=\"%s\">\n"
> +"%s"
>  "  <body>\n"
>  "    <div>\n";
>  
> @@ -72,6 +77,47 @@ static void ttml_write_time(AVIOContext *pb, const char tag[],
>                  tag, hour, min, sec, millisec);
>  }
>  
> +static int ttml_set_header_values_from_extradata(
> +    AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
> +{
> +    size_t additional_data_size =
> +        par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE;
> +

Missing check that extradata_size is >= TTMLENC_EXTRADATA_SIGNATURE_SIZE.

> +    if (!additional_data_size) {
> +        header_params->tt_element_params =
> +            av_strndup(ttml_default_namespacing,
> +                       sizeof(ttml_default_namespacing) - 1);
> +        header_params->pre_body_elements = av_strndup("", 1);

Why are you using av_strndup and not the ordinary av_strdup here?
Anyway, these allocations and the ones below are unnecessary as you only
need all of this when writing the header.

> +
> +        if (!header_params->tt_element_params ||
> +            !header_params->pre_body_elements)
> +            return AVERROR(ENOMEM);
> +
> +        return 0;
> +    }
> +
> +    {
> +        char *value =
> +            (char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE;
> +        size_t value_size = av_strnlen(value, additional_data_size);
> +
> +        if (!(header_params->tt_element_params = av_strndup(value, value_size)))
> +            return AVERROR(ENOMEM);
> +
> +        additional_data_size -= value_size + 1;
> +        value += value_size + 1;
> +        if (additional_data_size <= 0)
> +            return AVERROR_INVALIDDATA;
> +
> +        value_size = av_strnlen(value, additional_data_size);
> +
> +        if (!(header_params->pre_body_elements = av_strndup(value, value_size)))
> +            return AVERROR(ENOMEM);
> +
> +        return 0;
> +    }
> +}
> +
>  static int ttml_write_header(AVFormatContext *ctx)
>  {
>      TTMLMuxContext *ttml_ctx = ctx->priv_data;
> @@ -103,8 +149,21 @@ static int ttml_write_header(AVFormatContext *ctx)
>  
>          avpriv_set_pts_info(st, 64, 1, 1000);
>  
> -        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
> -            avio_printf(pb, ttml_header_text, printed_lang);
> +        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
> +            int ret = ttml_set_header_values_from_extradata(
> +                st->codecpar, &ttml_ctx->header_params);
> +            if (ret < 0) {
> +                av_log(ctx, AV_LOG_ERROR,
> +                       "Failed to parse TTML header values from extradata: "
> +                       "%s!\n", av_err2str(ret));
> +                return ret;
> +            }
> +
> +            avio_printf(pb, ttml_header_text,
> +                        ttml_ctx->header_params.tt_element_params,
> +                        printed_lang,
> +                        ttml_ctx->header_params.pre_body_elements);
> +        }
>      }
>  
>      return 0;
> @@ -159,6 +218,14 @@ static int ttml_write_trailer(AVFormatContext *ctx)
>      return 0;
>  }
>  
> +static void ttml_free(AVFormatContext *ctx)
> +{
> +    TTMLMuxContext *ttml_ctx = ctx->priv_data;
> +
> +    av_freep(&(ttml_ctx->header_params.tt_element_params));
> +    av_freep(&(ttml_ctx->header_params.pre_body_elements));

Unnecessary parentheses (on top of these allocations being unnecessary).

> +}
> +
>  AVOutputFormat ff_ttml_muxer = {
>      .name              = "ttml",
>      .long_name         = NULL_IF_CONFIG_SMALL("TTML subtitle"),
> @@ -171,4 +238,5 @@ AVOutputFormat ff_ttml_muxer = {
>      .write_header      = ttml_write_header,
>      .write_packet      = ttml_write_packet,
>      .write_trailer     = ttml_write_trailer,
> +    .deinit            = ttml_free,
>  };
>
Jan Ekström March 31, 2021, 6:54 a.m. UTC | #2
On Tue, Mar 30, 2021 at 12:19 PM Andreas Rheinhardt
<andreas.rheinhardt@outlook.com> wrote:
>
> Jan Ekström:
> > From: Jan Ekström <jan.ekstrom@24i.com>
> >
> > This way the encoder may pass on the following values to the muxer:
> > 1) Additional root "tt" element attributes, such as the subtitle
> >    canvas reference size.
> > 2) Anything before the body element of the document, such as regions
> >    in the head element, which can configure styles.
> >
> > Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
> > ---
> >  libavcodec/ttmlenc.h  |  5 +++
> >  libavformat/ttmlenc.c | 78 ++++++++++++++++++++++++++++++++++++++++---
> >  2 files changed, 78 insertions(+), 5 deletions(-)
> >
> > diff --git a/libavcodec/ttmlenc.h b/libavcodec/ttmlenc.h
> > index c1dd5ec990..c3bb11478d 100644
> > --- a/libavcodec/ttmlenc.h
> > +++ b/libavcodec/ttmlenc.h
> > @@ -25,4 +25,9 @@
> >  #define TTMLENC_EXTRADATA_SIGNATURE "lavc-ttmlenc"
> >  #define TTMLENC_EXTRADATA_SIGNATURE_SIZE (sizeof(TTMLENC_EXTRADATA_SIGNATURE) - 1)
> >
> > +static const char ttml_default_namespacing[] =
> > +"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
> > +"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
> > +"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n";
> > +
> >  #endif /* AVCODEC_TTMLENC_H */
> > diff --git a/libavformat/ttmlenc.c b/libavformat/ttmlenc.c
> > index 940f8bbd4e..5d9ad6b756 100644
> > --- a/libavformat/ttmlenc.c
> > +++ b/libavformat/ttmlenc.c
> > @@ -37,18 +37,23 @@ enum TTMLPacketType {
> >      PACKET_TYPE_DOCUMENT,
> >  };
> >
> > +struct TTMLHeaderParameters {
> > +    char *tt_element_params;
> > +    char *pre_body_elements;
> > +};
> > +
> >  typedef struct TTMLMuxContext {
> >      enum TTMLPacketType input_type;
> >      unsigned int document_written;
> > +    struct TTMLHeaderParameters header_params;
> >  } TTMLMuxContext;
> >
> >  static const char ttml_header_text[] =
> >  "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
> >  "<tt\n"
> > -"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
> > -"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
> > -"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n"
> > +"%s"
> >  "  xml:lang=\"%s\">\n"
> > +"%s"
> >  "  <body>\n"
> >  "    <div>\n";
> >
> > @@ -72,6 +77,47 @@ static void ttml_write_time(AVIOContext *pb, const char tag[],
> >                  tag, hour, min, sec, millisec);
> >  }
> >
> > +static int ttml_set_header_values_from_extradata(
> > +    AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
> > +{
> > +    size_t additional_data_size =
> > +        par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE;
> > +
>
> Missing check that extradata_size is >= TTMLENC_EXTRADATA_SIGNATURE_SIZE.

This function is only called if `ttml_ctx->input_type ==
PACKET_TYPE_PARAGRAPH`, which is only set if `extradata_size >=
TTMLENC_EXTRADATA_SIGNATURE_SIZE` (and if the , thus I thought that
checking it again would be unnecessary. Of course, if you think a
check is still needed, the following `!additional_data_size` check
`additional_data_size <= 0`.

>
> > +    if (!additional_data_size) {
> > +        header_params->tt_element_params =
> > +            av_strndup(ttml_default_namespacing,
> > +                       sizeof(ttml_default_namespacing) - 1);
> > +        header_params->pre_body_elements = av_strndup("", 1);
>
> Why are you using av_strndup and not the ordinary av_strdup here?

True, just got used to using the function with the max size defined.

> Anyway, these allocations and the ones below are unnecessary as you only
> need all of this when writing the header.

Yes, I could either utilize a struct, or pass a pointer to
values/struct. Just tried to be careful and not to re-utilize buffers
too easily from the extradata as-is.

>
> > +
> > +        if (!header_params->tt_element_params ||
> > +            !header_params->pre_body_elements)
> > +            return AVERROR(ENOMEM);
> > +
> > +        return 0;
> > +    }
> > +
> > +    {
> > +        char *value =
> > +            (char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE;
> > +        size_t value_size = av_strnlen(value, additional_data_size);
> > +
> > +        if (!(header_params->tt_element_params = av_strndup(value, value_size)))
> > +            return AVERROR(ENOMEM);
> > +
> > +        additional_data_size -= value_size + 1;
> > +        value += value_size + 1;
> > +        if (additional_data_size <= 0)
> > +            return AVERROR_INVALIDDATA;
> > +
> > +        value_size = av_strnlen(value, additional_data_size);
> > +
> > +        if (!(header_params->pre_body_elements = av_strndup(value, value_size)))
> > +            return AVERROR(ENOMEM);
> > +
> > +        return 0;
> > +    }
> > +}
> > +
> >  static int ttml_write_header(AVFormatContext *ctx)
> >  {
> >      TTMLMuxContext *ttml_ctx = ctx->priv_data;
> > @@ -103,8 +149,21 @@ static int ttml_write_header(AVFormatContext *ctx)
> >
> >          avpriv_set_pts_info(st, 64, 1, 1000);
> >
> > -        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
> > -            avio_printf(pb, ttml_header_text, printed_lang);
> > +        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
> > +            int ret = ttml_set_header_values_from_extradata(
> > +                st->codecpar, &ttml_ctx->header_params);
> > +            if (ret < 0) {
> > +                av_log(ctx, AV_LOG_ERROR,
> > +                       "Failed to parse TTML header values from extradata: "
> > +                       "%s!\n", av_err2str(ret));
> > +                return ret;
> > +            }
> > +
> > +            avio_printf(pb, ttml_header_text,
> > +                        ttml_ctx->header_params.tt_element_params,
> > +                        printed_lang,
> > +                        ttml_ctx->header_params.pre_body_elements);
> > +        }
> >      }
> >
> >      return 0;
> > @@ -159,6 +218,14 @@ static int ttml_write_trailer(AVFormatContext *ctx)
> >      return 0;
> >  }
> >
> > +static void ttml_free(AVFormatContext *ctx)
> > +{
> > +    TTMLMuxContext *ttml_ctx = ctx->priv_data;
> > +
> > +    av_freep(&(ttml_ctx->header_params.tt_element_params));
> > +    av_freep(&(ttml_ctx->header_params.pre_body_elements));
>
> Unnecessary parentheses (on top of these allocations being unnecessary).
>
> > +}
> > +
> >  AVOutputFormat ff_ttml_muxer = {
> >      .name              = "ttml",
> >      .long_name         = NULL_IF_CONFIG_SMALL("TTML subtitle"),
> > @@ -171,4 +238,5 @@ AVOutputFormat ff_ttml_muxer = {
> >      .write_header      = ttml_write_header,
> >      .write_packet      = ttml_write_packet,
> >      .write_trailer     = ttml_write_trailer,
> > +    .deinit            = ttml_free,
> >  };
> >
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
Andreas Rheinhardt March 31, 2021, 9:29 a.m. UTC | #3
Jan Ekström:
> On Tue, Mar 30, 2021 at 12:19 PM Andreas Rheinhardt
> <andreas.rheinhardt@outlook.com> wrote:
>>
>> Jan Ekström:
>>> From: Jan Ekström <jan.ekstrom@24i.com>
>>>
>>> This way the encoder may pass on the following values to the muxer:
>>> 1) Additional root "tt" element attributes, such as the subtitle
>>>    canvas reference size.
>>> 2) Anything before the body element of the document, such as regions
>>>    in the head element, which can configure styles.
>>>
>>> Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
>>> ---
>>>  libavcodec/ttmlenc.h  |  5 +++
>>>  libavformat/ttmlenc.c | 78 ++++++++++++++++++++++++++++++++++++++++---
>>>  2 files changed, 78 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/libavcodec/ttmlenc.h b/libavcodec/ttmlenc.h
>>> index c1dd5ec990..c3bb11478d 100644
>>> --- a/libavcodec/ttmlenc.h
>>> +++ b/libavcodec/ttmlenc.h
>>> @@ -25,4 +25,9 @@
>>>  #define TTMLENC_EXTRADATA_SIGNATURE "lavc-ttmlenc"
>>>  #define TTMLENC_EXTRADATA_SIGNATURE_SIZE (sizeof(TTMLENC_EXTRADATA_SIGNATURE) - 1)
>>>
>>> +static const char ttml_default_namespacing[] =
>>> +"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
>>> +"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
>>> +"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n";
>>> +
>>>  #endif /* AVCODEC_TTMLENC_H */
>>> diff --git a/libavformat/ttmlenc.c b/libavformat/ttmlenc.c
>>> index 940f8bbd4e..5d9ad6b756 100644
>>> --- a/libavformat/ttmlenc.c
>>> +++ b/libavformat/ttmlenc.c
>>> @@ -37,18 +37,23 @@ enum TTMLPacketType {
>>>      PACKET_TYPE_DOCUMENT,
>>>  };
>>>
>>> +struct TTMLHeaderParameters {
>>> +    char *tt_element_params;
>>> +    char *pre_body_elements;
>>> +};
>>> +
>>>  typedef struct TTMLMuxContext {
>>>      enum TTMLPacketType input_type;
>>>      unsigned int document_written;
>>> +    struct TTMLHeaderParameters header_params;
>>>  } TTMLMuxContext;
>>>
>>>  static const char ttml_header_text[] =
>>>  "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
>>>  "<tt\n"
>>> -"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
>>> -"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
>>> -"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n"
>>> +"%s"
>>>  "  xml:lang=\"%s\">\n"
>>> +"%s"
>>>  "  <body>\n"
>>>  "    <div>\n";
>>>
>>> @@ -72,6 +77,47 @@ static void ttml_write_time(AVIOContext *pb, const char tag[],
>>>                  tag, hour, min, sec, millisec);
>>>  }
>>>
>>> +static int ttml_set_header_values_from_extradata(
>>> +    AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
>>> +{
>>> +    size_t additional_data_size =
>>> +        par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE;
>>> +
>>
>> Missing check that extradata_size is >= TTMLENC_EXTRADATA_SIGNATURE_SIZE.
> 
> This function is only called if `ttml_ctx->input_type ==
> PACKET_TYPE_PARAGRAPH`, which is only set if `extradata_size >=
> TTMLENC_EXTRADATA_SIGNATURE_SIZE` (and if the , thus I thought that
> checking it again would be unnecessary. Of course, if you think a
> check is still needed, the following `!additional_data_size` check
> `additional_data_size <= 0`.
> 

Sorry for forgetting this; it was not immediate from the diff.
But notice that replacing the !additional_data_size check by
additional_data_size <= 0 is nonsense as additional_data_size has an
unsigned type.

>>
>>> +    if (!additional_data_size) {
>>> +        header_params->tt_element_params =
>>> +            av_strndup(ttml_default_namespacing,
>>> +                       sizeof(ttml_default_namespacing) - 1);
>>> +        header_params->pre_body_elements = av_strndup("", 1);
>>
>> Why are you using av_strndup and not the ordinary av_strdup here?
> 
> True, just got used to using the function with the max size defined.
> 
>> Anyway, these allocations and the ones below are unnecessary as you only
>> need all of this when writing the header.
> 
> Yes, I could either utilize a struct, or pass a pointer to
> values/struct. Just tried to be careful and not to re-utilize buffers
> too easily from the extradata as-is.

And why are you trying not to re-utilize buffers from extradata?

> 
>>
>>> +
>>> +        if (!header_params->tt_element_params ||
>>> +            !header_params->pre_body_elements)
>>> +            return AVERROR(ENOMEM);
>>> +
>>> +        return 0;
>>> +    }
>>> +
>>> +    {
>>> +        char *value =
>>> +            (char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE;
>>> +        size_t value_size = av_strnlen(value, additional_data_size);
>>> +
>>> +        if (!(header_params->tt_element_params = av_strndup(value, value_size)))
>>> +            return AVERROR(ENOMEM);
>>> +
>>> +        additional_data_size -= value_size + 1;
>>> +        value += value_size + 1;
>>> +        if (additional_data_size <= 0)
>>> +            return AVERROR_INVALIDDATA;
>>> +
>>> +        value_size = av_strnlen(value, additional_data_size);
>>> +
>>> +        if (!(header_params->pre_body_elements = av_strndup(value, value_size)))
>>> +            return AVERROR(ENOMEM);
>>> +
>>> +        return 0;
>>> +    }
>>> +}
>>> +
>>>  static int ttml_write_header(AVFormatContext *ctx)
>>>  {
>>>      TTMLMuxContext *ttml_ctx = ctx->priv_data;
>>> @@ -103,8 +149,21 @@ static int ttml_write_header(AVFormatContext *ctx)
>>>
>>>          avpriv_set_pts_info(st, 64, 1, 1000);
>>>
>>> -        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
>>> -            avio_printf(pb, ttml_header_text, printed_lang);
>>> +        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
>>> +            int ret = ttml_set_header_values_from_extradata(
>>> +                st->codecpar, &ttml_ctx->header_params);
>>> +            if (ret < 0) {
>>> +                av_log(ctx, AV_LOG_ERROR,
>>> +                       "Failed to parse TTML header values from extradata: "
>>> +                       "%s!\n", av_err2str(ret));
>>> +                return ret;
>>> +            }
>>> +
>>> +            avio_printf(pb, ttml_header_text,
>>> +                        ttml_ctx->header_params.tt_element_params,
>>> +                        printed_lang,
>>> +                        ttml_ctx->header_params.pre_body_elements);
>>> +        }
>>>      }
>>>
>>>      return 0;
>>> @@ -159,6 +218,14 @@ static int ttml_write_trailer(AVFormatContext *ctx)
>>>      return 0;
>>>  }
>>>
>>> +static void ttml_free(AVFormatContext *ctx)
>>> +{
>>> +    TTMLMuxContext *ttml_ctx = ctx->priv_data;
>>> +
>>> +    av_freep(&(ttml_ctx->header_params.tt_element_params));
>>> +    av_freep(&(ttml_ctx->header_params.pre_body_elements));
>>
>> Unnecessary parentheses (on top of these allocations being unnecessary).
>>
>>> +}
>>> +
>>>  AVOutputFormat ff_ttml_muxer = {
>>>      .name              = "ttml",
>>>      .long_name         = NULL_IF_CONFIG_SMALL("TTML subtitle"),
>>> @@ -171,4 +238,5 @@ AVOutputFormat ff_ttml_muxer = {
>>>      .write_header      = ttml_write_header,
>>>      .write_packet      = ttml_write_packet,
>>>      .write_trailer     = ttml_write_trailer,
>>> +    .deinit            = ttml_free,
>>>  };
>>>
>>
diff mbox series

Patch

diff --git a/libavcodec/ttmlenc.h b/libavcodec/ttmlenc.h
index c1dd5ec990..c3bb11478d 100644
--- a/libavcodec/ttmlenc.h
+++ b/libavcodec/ttmlenc.h
@@ -25,4 +25,9 @@ 
 #define TTMLENC_EXTRADATA_SIGNATURE "lavc-ttmlenc"
 #define TTMLENC_EXTRADATA_SIGNATURE_SIZE (sizeof(TTMLENC_EXTRADATA_SIGNATURE) - 1)
 
+static const char ttml_default_namespacing[] =
+"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
+"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
+"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n";
+
 #endif /* AVCODEC_TTMLENC_H */
diff --git a/libavformat/ttmlenc.c b/libavformat/ttmlenc.c
index 940f8bbd4e..5d9ad6b756 100644
--- a/libavformat/ttmlenc.c
+++ b/libavformat/ttmlenc.c
@@ -37,18 +37,23 @@  enum TTMLPacketType {
     PACKET_TYPE_DOCUMENT,
 };
 
+struct TTMLHeaderParameters {
+    char *tt_element_params;
+    char *pre_body_elements;
+};
+
 typedef struct TTMLMuxContext {
     enum TTMLPacketType input_type;
     unsigned int document_written;
+    struct TTMLHeaderParameters header_params;
 } TTMLMuxContext;
 
 static const char ttml_header_text[] =
 "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n"
 "<tt\n"
-"  xmlns=\"http://www.w3.org/ns/ttml\"\n"
-"  xmlns:ttm=\"http://www.w3.org/ns/ttml#metadata\"\n"
-"  xmlns:tts=\"http://www.w3.org/ns/ttml#styling\"\n"
+"%s"
 "  xml:lang=\"%s\">\n"
+"%s"
 "  <body>\n"
 "    <div>\n";
 
@@ -72,6 +77,47 @@  static void ttml_write_time(AVIOContext *pb, const char tag[],
                 tag, hour, min, sec, millisec);
 }
 
+static int ttml_set_header_values_from_extradata(
+    AVCodecParameters *par, struct TTMLHeaderParameters *header_params)
+{
+    size_t additional_data_size =
+        par->extradata_size - TTMLENC_EXTRADATA_SIGNATURE_SIZE;
+
+    if (!additional_data_size) {
+        header_params->tt_element_params =
+            av_strndup(ttml_default_namespacing,
+                       sizeof(ttml_default_namespacing) - 1);
+        header_params->pre_body_elements = av_strndup("", 1);
+
+        if (!header_params->tt_element_params ||
+            !header_params->pre_body_elements)
+            return AVERROR(ENOMEM);
+
+        return 0;
+    }
+
+    {
+        char *value =
+            (char *)par->extradata + TTMLENC_EXTRADATA_SIGNATURE_SIZE;
+        size_t value_size = av_strnlen(value, additional_data_size);
+
+        if (!(header_params->tt_element_params = av_strndup(value, value_size)))
+            return AVERROR(ENOMEM);
+
+        additional_data_size -= value_size + 1;
+        value += value_size + 1;
+        if (additional_data_size <= 0)
+            return AVERROR_INVALIDDATA;
+
+        value_size = av_strnlen(value, additional_data_size);
+
+        if (!(header_params->pre_body_elements = av_strndup(value, value_size)))
+            return AVERROR(ENOMEM);
+
+        return 0;
+    }
+}
+
 static int ttml_write_header(AVFormatContext *ctx)
 {
     TTMLMuxContext *ttml_ctx = ctx->priv_data;
@@ -103,8 +149,21 @@  static int ttml_write_header(AVFormatContext *ctx)
 
         avpriv_set_pts_info(st, 64, 1, 1000);
 
-        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH)
-            avio_printf(pb, ttml_header_text, printed_lang);
+        if (ttml_ctx->input_type == PACKET_TYPE_PARAGRAPH) {
+            int ret = ttml_set_header_values_from_extradata(
+                st->codecpar, &ttml_ctx->header_params);
+            if (ret < 0) {
+                av_log(ctx, AV_LOG_ERROR,
+                       "Failed to parse TTML header values from extradata: "
+                       "%s!\n", av_err2str(ret));
+                return ret;
+            }
+
+            avio_printf(pb, ttml_header_text,
+                        ttml_ctx->header_params.tt_element_params,
+                        printed_lang,
+                        ttml_ctx->header_params.pre_body_elements);
+        }
     }
 
     return 0;
@@ -159,6 +218,14 @@  static int ttml_write_trailer(AVFormatContext *ctx)
     return 0;
 }
 
+static void ttml_free(AVFormatContext *ctx)
+{
+    TTMLMuxContext *ttml_ctx = ctx->priv_data;
+
+    av_freep(&(ttml_ctx->header_params.tt_element_params));
+    av_freep(&(ttml_ctx->header_params.pre_body_elements));
+}
+
 AVOutputFormat ff_ttml_muxer = {
     .name              = "ttml",
     .long_name         = NULL_IF_CONFIG_SMALL("TTML subtitle"),
@@ -171,4 +238,5 @@  AVOutputFormat ff_ttml_muxer = {
     .write_header      = ttml_write_header,
     .write_packet      = ttml_write_packet,
     .write_trailer     = ttml_write_trailer,
+    .deinit            = ttml_free,
 };