int avformat_write_header(AVFormatContext *s, AVDictionary **options) { int ret = 0, i; AVStream *st; AVDictionary *tmp = NULL; AVCodecContext *codec = NULL; AVOutputFormat *of = s->oformat; if (options) av_dict_copy(&tmp, *options, 0); if ((ret = av_opt_set_dict(s, &tmp)) < 0) goto fail; // some sanity checks if (s->nb_streams == 0 && !(of->flags & AVFMT_NOSTREAMS)) { av_log(s, AV_LOG_ERROR, "no streams\n"); ret = AVERROR(EINVAL); goto fail; } for (i = 0; i < s->nb_streams; i++) { st = s->streams[i]; codec = st->codec; switch (codec->codec_type) { case AVMEDIA_TYPE_AUDIO: if (codec->sample_rate <= 0) { av_log(s, AV_LOG_ERROR, "sample rate not set\n"); ret = AVERROR(EINVAL); goto fail; } if (!codec->block_align) codec->block_align = codec->channels * av_get_bits_per_sample(codec->codec_id) >> 3; break; case AVMEDIA_TYPE_VIDEO: if (codec->time_base.num <= 0 || codec->time_base.den <= 0) { //FIXME audio too? av_log(s, AV_LOG_ERROR, "time base not set\n"); ret = AVERROR(EINVAL); goto fail; } if ((codec->width <= 0 || codec->height <= 0) && !(of->flags & AVFMT_NODIMENSIONS)) { av_log(s, AV_LOG_ERROR, "dimensions not set\n"); ret = AVERROR(EINVAL); goto fail; } if (av_cmp_q(st->sample_aspect_ratio, codec->sample_aspect_ratio)) { av_log(s, AV_LOG_ERROR, "Aspect ratio mismatch between muxer " "(%d/%d) and encoder layer (%d/%d)\n", st->sample_aspect_ratio.num, st->sample_aspect_ratio.den, codec->sample_aspect_ratio.num, codec->sample_aspect_ratio.den); ret = AVERROR(EINVAL); goto fail; } break; } if (of->codec_tag) { if (codec->codec_tag && codec->codec_id == AV_CODEC_ID_RAWVIDEO && !av_codec_get_tag(of->codec_tag, codec->codec_id) && !validate_codec_tag(s, st)) { // the current rawvideo encoding system ends up setting // the wrong codec_tag for avi, we override it here codec->codec_tag = 0; } if (codec->codec_tag) { if (!validate_codec_tag(s, st)) { char tagbuf[32]; av_get_codec_tag_string(tagbuf, sizeof(tagbuf), codec->codec_tag); av_log(s, AV_LOG_ERROR, "Tag %s/0x%08x incompatible with output codec id '%d'\n", tagbuf, codec->codec_tag, codec->codec_id); ret = AVERROR_INVALIDDATA; goto fail; } } else codec->codec_tag = av_codec_get_tag(of->codec_tag, codec->codec_id); } if (of->flags & AVFMT_GLOBALHEADER && !(codec->flags & CODEC_FLAG_GLOBAL_HEADER)) av_log(s, AV_LOG_WARNING, "Codec for stream %d does not use global headers " "but container format requires global headers\n", i); } if (!s->priv_data && of->priv_data_size > 0) { s->priv_data = av_mallocz(of->priv_data_size); if (!s->priv_data) { ret = AVERROR(ENOMEM); goto fail; } if (of->priv_class) { *(const AVClass **)s->priv_data = of->priv_class; av_opt_set_defaults(s->priv_data); if ((ret = av_opt_set_dict(s->priv_data, &tmp)) < 0) goto fail; } } /* set muxer identification string */ if (s->nb_streams && !(s->streams[0]->codec->flags & CODEC_FLAG_BITEXACT)) { av_dict_set(&s->metadata, "encoder", LIBAVFORMAT_IDENT, 0); } if (s->oformat->write_header) { ret = s->oformat->write_header(s); if (ret < 0) goto fail; } /* init PTS generation */ for (i = 0; i < s->nb_streams; i++) { int64_t den = AV_NOPTS_VALUE; st = s->streams[i]; switch (st->codec->codec_type) { case AVMEDIA_TYPE_AUDIO: den = (int64_t)st->time_base.num * st->codec->sample_rate; break; case AVMEDIA_TYPE_VIDEO: den = (int64_t)st->time_base.num * st->codec->time_base.den; break; default: break; } if (den != AV_NOPTS_VALUE) { if (den <= 0) { ret = AVERROR_INVALIDDATA; goto fail; } frac_init(&st->pts, 0, 0, den); } } if (options) { av_dict_free(options); *options = tmp; } return 0; fail: av_dict_free(&tmp); return ret; }