static int ast_write_header(AVFormatContext *s) { ASTMuxContext *ast = s->priv_data; AVIOContext *pb = s->pb; AVCodecContext *enc; unsigned int codec_tag; if (s->nb_streams == 1) { enc = s->streams[0]->codec; } else { av_log(s, AV_LOG_ERROR, "only one stream is supported\n"); return AVERROR(EINVAL); } if (enc->codec_id == AV_CODEC_ID_ADPCM_AFC) { av_log(s, AV_LOG_ERROR, "muxing ADPCM AFC is not implemented\n"); return AVERROR_PATCHWELCOME; } codec_tag = ff_codec_get_tag(ff_codec_ast_tags, enc->codec_id); if (!codec_tag) { av_log(s, AV_LOG_ERROR, "unsupported codec\n"); return AVERROR(EINVAL); } if (ast->loopstart && ast->loopend && ast->loopstart >= ast->loopend) { av_log(s, AV_LOG_ERROR, "loopend can't be less or equal to loopstart\n"); return AVERROR(EINVAL); } /* Convert milliseconds to samples */ CHECK_LOOP(start) CHECK_LOOP(end) ffio_wfourcc(pb, "STRM"); ast->size = avio_tell(pb); avio_wb32(pb, 0); /* File size minus header */ avio_wb16(pb, codec_tag); avio_wb16(pb, 16); /* Bit depth */ avio_wb16(pb, enc->channels); avio_wb16(pb, 0xFFFF); avio_wb32(pb, enc->sample_rate); ast->samples = avio_tell(pb); avio_wb32(pb, 0); /* Number of samples */ avio_wb32(pb, 0); /* Loopstart */ avio_wb32(pb, 0); /* Loopend */ avio_wb32(pb, 0); /* Size of first block */ /* Unknown */ avio_wb32(pb, 0); avio_wl32(pb, 0x7F); avio_wb64(pb, 0); avio_wb64(pb, 0); avio_wb32(pb, 0); avio_flush(pb); return 0; }