[FFmpeg-devel] [PATCH] lavfi: add subtitles filter.
Stefano Sabatini
stefasab at gmail.com
Thu Nov 29 11:08:47 CET 2012
On date Thursday 2012-11-29 03:33:01 +0100, Clément Bœsch encoded:
> TODO: lavfi micro bump
minor
> TODO: Changelog
> ---
> Yes I know, you guys would prefer that we add lavfi subtitles support instead.
> Unfortunately, I don't see this in a near future. And on the other hand, this
> is quite handy for users who just want to hardsub a .SRT file. And we can also
> ffplay ... -vf subtitles=sub.srt to watch a movie with external text subtitles
> after this patch.
> ---
> configure | 1 +
> doc/filters.texi | 72 ++++++++++++-----------
> libavfilter/Makefile | 1 +
> libavfilter/allfilters.c | 1 +
> libavfilter/vf_ass.c | 146 ++++++++++++++++++++++++++++++++++++++++++-----
> 5 files changed, 175 insertions(+), 46 deletions(-)
>
> diff --git a/configure b/configure
> index a7990f5..6276440 100755
> --- a/configure
> +++ b/configure
> @@ -1933,6 +1933,7 @@ aconvert_filter_deps="swresample"
> amovie_filter_deps="avcodec avformat"
> aresample_filter_deps="swresample"
> ass_filter_deps="libass"
> +subtitles_filter_deps="avformat avcodec libass"
> asyncts_filter_deps="avresample"
> atempo_filter_deps="avcodec rdft"
> blackframe_filter_deps="gpl"
> diff --git a/doc/filters.texi b/doc/filters.texi
> index 0b57e03..22ce415 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -1274,38 +1274,9 @@ overlay to a video stream, consider the @var{overlay} filter instead.
>
> @section ass
>
> -Draw ASS (Advanced Substation Alpha) subtitles on top of input video
> -using the libass library.
> -
> -To enable compilation of this filter you need to configure FFmpeg with
> - at code{--enable-libass}.
> -
> -This filter accepts the following named options, expressed as a
> -sequence of @var{key}=@var{value} pairs, separated by ":".
> -
> - at table @option
> - at item filename, f
> -Set the filename of the ASS file to read. It must be specified.
> -
> - at item original_size
> -Specify the size of the original video, the video for which the ASS file
> -was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
> -necessary to correctly scale the fonts if the aspect ratio has been changed.
> - at end table
> -
> -If the first key is not specified, it is assumed that the first value
> -specifies the @option{filename}.
> -
> -For example, to render the file @file{sub.ass} on top of the input
> -video, use the command:
> - at example
> -ass=sub.ass
> - at end example
> -
> -which is equivalent to:
> - at example
> -ass=filename=sub.ass
> - at end example
> +Same as the @ref{subtitles} filter, except that it doesn't require libavcodec
> +and libavformat to work. On the other hand, it is limited to ASS (Advanced
> +Substation Alpha) subtitles files.
>
> @section bbox
>
> @@ -3735,6 +3706,43 @@ a pixel should be blurred or not. A value of 0 will filter all the
> image, a value included in [0,30] will filter flat areas and a value
> included in [-30,0] will filter edges.
>
> + at anchor{subtitles}
> + at section subtitles
> +
> +Draw subtitles subtitles on top of input video using the libass library.
repetition repetition
> +
> +To enable compilation of this filter you need to configure FFmpeg with
> + at code{--enable-libass}. This filter also requires a build with libavcodec and
> +libavformat to convert the passed subtitles file to ASS (Advanced Substation
> +Alpha) subtitles format.
> +
> +This filter accepts the following named options, expressed as a
> +sequence of @var{key}=@var{value} pairs, separated by ":".
> +
> + at table @option
> + at item filename, f
> +Set the filename of the subtitle file to read. It must be specified.
> +
> + at item original_size
> +Specify the size of the original video, the video for which the ASS file
> +was composed. Due to a misdesign in ASS aspect ratio arithmetic, this is
> +necessary to correctly scale the fonts if the aspect ratio has been changed.
> + at end table
> +
> +If the first key is not specified, it is assumed that the first value
> +specifies the @option{filename}.
> +
> +For example, to render the file @file{sub.srt} on top of the input
> +video, use the command:
> + at example
> +subtitles=sub.srt
> + at end example
> +
> +which is equivalent to:
> + at example
> +subtitles=filename=sub.srt
> + at end example
> +
> @section split
>
> Split input video into several identical outputs.
> diff --git a/libavfilter/Makefile b/libavfilter/Makefile
> index 0e49912..377bd4d 100644
> --- a/libavfilter/Makefile
> +++ b/libavfilter/Makefile
> @@ -134,6 +134,7 @@ OBJS-$(CONFIG_SETTB_FILTER) += f_settb.o
> OBJS-$(CONFIG_SHOWINFO_FILTER) += vf_showinfo.o
> OBJS-$(CONFIG_SMARTBLUR_FILTER) += vf_smartblur.o
> OBJS-$(CONFIG_SPLIT_FILTER) += split.o
> +OBJS-$(CONFIG_SUBTITLES_FILTER) += vf_ass.o
> OBJS-$(CONFIG_SUPER2XSAI_FILTER) += vf_super2xsai.o
> OBJS-$(CONFIG_SWAPUV_FILTER) += vf_swapuv.o
> OBJS-$(CONFIG_THUMBNAIL_FILTER) += vf_thumbnail.o
> diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
> index 746e713..5a1f939 100644
> --- a/libavfilter/allfilters.c
> +++ b/libavfilter/allfilters.c
> @@ -126,6 +126,7 @@ void avfilter_register_all(void)
> REGISTER_FILTER (SHOWINFO, showinfo, vf);
> REGISTER_FILTER (SMARTBLUR, smartblur, vf);
> REGISTER_FILTER (SPLIT, split, vf);
> + REGISTER_FILTER (SUBTITLES, subtitles, vf);
> REGISTER_FILTER (SUPER2XSAI, super2xsai, vf);
> REGISTER_FILTER (SWAPUV, swapuv, vf);
> REGISTER_FILTER (THUMBNAIL, thumbnail, vf);
> diff --git a/libavfilter/vf_ass.c b/libavfilter/vf_ass.c
> index 5f96202..dee95fa 100644
> --- a/libavfilter/vf_ass.c
> +++ b/libavfilter/vf_ass.c
> @@ -28,6 +28,11 @@
>
> #include <ass/ass.h>
>
> +#include "config.h"
> +#if CONFIG_SUBTITLES_FILTER
> +# include "libavcodec/avcodec.h"
> +# include "libavformat/avformat.h"
> +#endif
> #include "libavutil/avstring.h"
> #include "libavutil/imgutils.h"
> #include "libavutil/opt.h"
> @@ -53,15 +58,13 @@ typedef struct {
> #define OFFSET(x) offsetof(AssContext, x)
> #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
>
> -static const AVOption ass_options[] = {
> +static const AVOption options[] = {
> {"filename", "set the filename of the ASS file to read", OFFSET(filename), AV_OPT_TYPE_STRING, {.str = NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
> {"f", "set the filename of the ASS file to read", OFFSET(filename), AV_OPT_TYPE_STRING, {.str = NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
> {"original_size", "set the size of the original video (used to scale fonts)", OFFSET(original_w), AV_OPT_TYPE_IMAGE_SIZE, {.str = NULL}, CHAR_MIN, CHAR_MAX, FLAGS },
> {NULL},
> };
>
> -AVFILTER_DEFINE_CLASS(ass);
> -
> /* libass supports a log level ranging from 0 to 7 */
> static const int ass_libavfilter_log_level_map[] = {
> AV_LOG_QUIET, /* 0 */
> @@ -82,13 +85,13 @@ static void ass_log(int ass_level, const char *fmt, va_list args, void *ctx)
> av_log(ctx, level, "\n");
> }
>
> -static av_cold int init(AVFilterContext *ctx, const char *args)
> +static av_cold int init(AVFilterContext *ctx, const char *args, const AVClass *class)
> {
> AssContext *ass = ctx->priv;
> static const char *shorthand[] = { "filename", NULL };
> int ret;
>
> - ass->class = &ass_class;
> + ass->class = class;
> av_opt_set_defaults(ass);
>
> if ((ret = av_opt_set_from_string(ass, args, shorthand, "=", ":")) < 0)
> @@ -112,14 +115,6 @@ static av_cold int init(AVFilterContext *ctx, const char *args)
> return AVERROR(EINVAL);
> }
>
> - ass->track = ass_read_file(ass->library, ass->filename, NULL);
> - if (!ass->track) {
> - av_log(ctx, AV_LOG_ERROR,
> - "Could not create a libass track when reading file '%s'\n",
> - ass->filename);
> - return AVERROR(EINVAL);
> - }
> -
> ass_set_fonts(ass->renderer, NULL, NULL, 1, NULL, 1);
> return 0;
> }
> @@ -215,14 +210,137 @@ static const AVFilterPad ass_outputs[] = {
> { NULL }
> };
>
> +#if CONFIG_ASS_FILTER
> +
> +#define ass_options options
> +AVFILTER_DEFINE_CLASS(ass);
> +
> +static av_cold int init_ass(AVFilterContext *ctx, const char *args)
> +{
> + AssContext *ass = ctx->priv;
> + int ret = init(ctx, args, &ass_class);
> +
> + if (ret < 0)
> + return ret;
> +
> + ass->track = ass_read_file(ass->library, ass->filename, NULL);
> + if (!ass->track) {
> + av_log(ctx, AV_LOG_ERROR,
> + "Could not create a libass track when reading file '%s'\n",
> + ass->filename);
> + return AVERROR(EINVAL);
> + }
> + return 0;
> +}
> +
> AVFilter avfilter_vf_ass = {
> .name = "ass",
> .description = NULL_IF_CONFIG_SMALL("Render subtitles onto input video using the libass library."),
> .priv_size = sizeof(AssContext),
> - .init = init,
> + .init = init_ass,
> .uninit = uninit,
> .query_formats = query_formats,
> .inputs = ass_inputs,
> .outputs = ass_outputs,
> .priv_class = &ass_class,
> };
> +#endif
> +
> +#if CONFIG_SUBTITLES_FILTER
> +
> +#define subtitles_options options
> +AVFILTER_DEFINE_CLASS(subtitles);
> +
> +static av_cold int init_subtitles(AVFilterContext *ctx, const char *args)
> +{
> + int ret, sid;
> + AVFormatContext *fmt = NULL;
> + AVCodecContext *dec_ctx = NULL;
> + AVCodec *dec = NULL;
> + AVStream *st;
> + AVPacket pkt;
> + AssContext *ass = ctx->priv;
> +
> + /* Init libass */
> + ret = init(ctx, args, &subtitles_class);
> + if (ret < 0)
> + return ret;
> + ass->track = ass_new_track(ass->library);
> + if (!ass->track) {
> + av_log(ctx, AV_LOG_ERROR, "Could not create a libass track\n");
> + return AVERROR(EINVAL);
> + }
> +
> + /* Open subtitle file */
> + ret = avformat_open_input(&fmt, ass->filename, NULL, NULL);
> + if (ret < 0)
> + goto end;
> + ret = avformat_find_stream_info(fmt, NULL);
> + if (ret < 0)
> + goto end;
> +
> + /* Locate subtitle stream */
> + ret = av_find_best_stream(fmt, AVMEDIA_TYPE_SUBTITLE, -1, -1, NULL, 0);
> + if (ret < 0)
> + goto end;
> + sid = ret;
> + st = fmt->streams[sid];
> +
> + /* Open decoder */
> + dec_ctx = st->codec;
> + dec = avcodec_find_decoder(dec_ctx->codec_id);
> + if (!dec) {
> + av_log(NULL, AV_LOG_ERROR, "Failed to find subtitle codec\n");
Here you could print the name of the codec and aid the user.
> + return AVERROR(EINVAL);
> + }
> + ret = avcodec_open2(dec_ctx, dec, NULL);
> + if (ret < 0)
> + goto end;
> +
> + /* Decode subtitles and push them into the renderer (libass) */
> + if (dec_ctx->subtitle_header)
> + ass_process_codec_private(ass->track,
> + dec_ctx->subtitle_header,
> + dec_ctx->subtitle_header_size);
> + av_init_packet(&pkt);
> + pkt.data = NULL;
> + pkt.size = 0;
> + while (av_read_frame(fmt, &pkt) >= 0) {
> + int i, got_subtitle;
> + AVSubtitle sub;
> +
> + if (pkt.stream_index == sid) {
> + ret = avcodec_decode_subtitle2(dec_ctx, &sub, &got_subtitle, &pkt);
> + if (ret < 0 || !got_subtitle)
> + break;
> + for (i = 0; i < sub.num_rects; i++) {
> + char *ass_line = sub.rects[i]->ass;
> + ass_process_data(ass->track, ass_line, strlen(ass_line));
> + }
> + }
> + av_free_packet(&pkt);
> + avsubtitle_free(&sub);
> + }
> +
> +end:
> + if (fmt)
> + avformat_close_input(&fmt);
> + if (dec_ctx)
> + avcodec_close(dec_ctx);
> + if (!ret)
looks wrong
> + av_log(NULL, AV_LOG_INFO, "Subtitle %s loaded\n", ass->filename);
Also you may want to issue a warning/error in case of decoding error.
> + return ret;
> +}
> +
> +AVFilter avfilter_vf_subtitles = {
> + .name = "subtitles",
> + .description = NULL_IF_CONFIG_SMALL("Render subtitles onto input video using the libass library."),
> + .priv_size = sizeof(AssContext),
> + .init = init_subtitles,
> + .uninit = uninit,
> + .query_formats = query_formats,
> + .inputs = ass_inputs,
> + .outputs = ass_outputs,
> + .priv_class = &subtitles_class,
> +};
> +#endif
Very nice "hack" otherwise ;-).
--
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