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 subtitles file */ ret = avformat_open_input(&fmt, ass->filename, NULL, NULL); if (ret < 0) { av_log(ctx, AV_LOG_ERROR, "Unable to open %s\n", ass->filename); goto end; } ret = avformat_find_stream_info(fmt, NULL); if (ret < 0) goto end; /* Locate subtitles stream */ ret = av_find_best_stream(fmt, AVMEDIA_TYPE_SUBTITLE, -1, -1, NULL, 0); if (ret < 0) { av_log(ctx, AV_LOG_ERROR, "Unable to locate subtitle stream in %s\n", ass->filename); 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(ctx, AV_LOG_ERROR, "Failed to find subtitle codec %s\n", avcodec_get_name(dec_ctx->codec_id)); 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; if (!ass_line) break; 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); return ret; }