From 7040c9fac246ad9f8333d635045d24bc107ecfa8 Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Mon, 10 Sep 2012 14:44:32 +0200 Subject: mp3enc: write Xing TOC MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Based on the code by: Peter Belkner , Michael Niedermayer , Clément Bœsch , Reimar Döffinger , and Tobias Rapp Alex Converse Signed-off-by: Anton Khirnov --- libavformat/mp3enc.c | 140 +++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 120 insertions(+), 20 deletions(-) (limited to 'libavformat/mp3enc.c') diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c index 6a6e60226e..c969777255 100644 --- a/libavformat/mp3enc.c +++ b/libavformat/mp3enc.c @@ -74,12 +74,27 @@ static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf) return count; } +#define XING_NUM_BAGS 400 +#define XING_TOC_SIZE 100 +// maximum size of the xing frame: offset/Xing/flags/frames/size/TOC +#define XING_MAX_SIZE (32 + 4 + 4 + 4 + 4 + XING_TOC_SIZE) + typedef struct MP3Context { const AVClass *class; ID3v2EncContext id3; int id3v2_version; int write_id3v1; - int64_t nb_frames_offset; + + /* xing header */ + int64_t xing_offset; + int32_t frames; + int32_t size; + uint32_t want; + uint32_t seen; + uint32_t pos; + uint64_t bag[XING_NUM_BAGS]; + int initial_bitrate; + int has_variable_bitrate; /* index of the audio stream */ int audio_stream_idx; @@ -92,15 +107,17 @@ typedef struct MP3Context { static const uint8_t xing_offtbl[2][2] = {{32, 17}, {17, 9}}; -/* insert a dummy frame containing number of frames */ +/* + * Write an empty XING header and initialize respective data. + */ static void mp3_write_xing(AVFormatContext *s) { MP3Context *mp3 = s->priv_data; AVCodecContext *codec = s->streams[mp3->audio_stream_idx]->codec; - int bitrate_idx = 1; // 32 kbps int32_t header; MPADecodeHeader mpah; int srate_idx, i, channels; + int bitrate_idx; int xing_offset; int ver = 0; @@ -132,6 +149,9 @@ static void mp3_write_xing(AVFormatContext *s) return; } + /* 64 kbps frame, should be large enough */ + bitrate_idx = (ver == 3) ? 5 : 8; + /* dummy MPEG audio header */ header = 0xff << 24; // sync header |= (0x7 << 5 | ver << 3 | 0x1 << 1 | 0x1) << 16; // sync/audio-version/layer 3/no crc*/ @@ -141,17 +161,78 @@ static void mp3_write_xing(AVFormatContext *s) avpriv_mpegaudio_decode_header(&mpah, header); + av_assert0(mpah.frame_size >= XING_MAX_SIZE); + xing_offset = xing_offtbl[ver != 3][codec->channels == 1]; ffio_fill(s->pb, 0, xing_offset); + mp3->xing_offset = avio_tell(s->pb); ffio_wfourcc(s->pb, "Xing"); - avio_wb32(s->pb, 0x1); // only number of frames - mp3->nb_frames_offset = avio_tell(s->pb); - avio_wb32(s->pb, 0); + avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames / size / TOC - mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4; + mp3->size = mpah.frame_size; + mp3->want = 1; + + avio_wb32(s->pb, 0); // frames + avio_wb32(s->pb, 0); // size + + // TOC + for (i = 0; i < XING_TOC_SIZE; i++) + avio_w8(s->pb, 255 * i / XING_TOC_SIZE); + + mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4 + 4 + XING_TOC_SIZE; ffio_fill(s->pb, 0, mpah.frame_size); } +/* + * Add a frame to XING data. + * Following lame's "VbrTag.c". + */ +static void mp3_xing_add_frame(MP3Context *mp3, AVPacket *pkt) +{ + int i; + + mp3->frames++; + mp3->seen++; + mp3->size += pkt->size; + + if (mp3->want == mp3->seen) { + mp3->bag[mp3->pos] = mp3->size; + + if (XING_NUM_BAGS == ++mp3->pos) { + /* shrink table to half size by throwing away each second bag. */ + for (i = 1; i < XING_NUM_BAGS; i += 2) + mp3->bag[i / 2] = mp3->bag[i]; + + /* double wanted amount per bag. */ + mp3->want *= 2; + /* adjust current position to half of table size. */ + mp3->pos = XING_NUM_BAGS / 2; + } + + mp3->seen = 0; + } +} + +static int mp3_write_audio_packet(AVFormatContext *s, AVPacket *pkt) +{ + MP3Context *mp3 = s->priv_data; + + if (mp3->xing_offset && pkt->size >= 4) { + MPADecodeHeader c; + + avpriv_mpegaudio_decode_header(&c, AV_RB32(pkt->data)); + + if (!mp3->initial_bitrate) + mp3->initial_bitrate = c.bit_rate; + if ((c.bit_rate == 0) || (mp3->initial_bitrate != c.bit_rate)) + mp3->has_variable_bitrate = 1; + + mp3_xing_add_frame(mp3, pkt); + } + + return ff_raw_write_packet(s, pkt); +} + static int mp3_queue_flush(AVFormatContext *s) { MP3Context *mp3 = s->priv_data; @@ -162,7 +243,7 @@ static int mp3_queue_flush(AVFormatContext *s) mp3_write_xing(s); while ((pktl = mp3->queue)) { - if (write && (ret = ff_raw_write_packet(s, &pktl->pkt)) < 0) + if (write && (ret = mp3_write_audio_packet(s, &pktl->pkt)) < 0) write = 0; av_free_packet(&pktl->pkt); mp3->queue = pktl->next; @@ -172,30 +253,50 @@ static int mp3_queue_flush(AVFormatContext *s) return ret; } +static void mp3_update_xing(AVFormatContext *s) +{ + MP3Context *mp3 = s->priv_data; + int i; + + /* replace "Xing" identification string with "Info" for CBR files. */ + if (!mp3->has_variable_bitrate) { + avio_seek(s->pb, mp3->xing_offset, SEEK_SET); + ffio_wfourcc(s->pb, "Info"); + } + + avio_seek(s->pb, mp3->xing_offset + 8, SEEK_SET); + avio_wb32(s->pb, mp3->frames); + avio_wb32(s->pb, mp3->size); + + avio_w8(s->pb, 0); // first toc entry has to be zero. + + for (i = 1; i < XING_TOC_SIZE; ++i) { + int j = i * mp3->pos / XING_TOC_SIZE; + int seek_point = 256LL * mp3->bag[j] / mp3->size; + avio_w8(s->pb, FFMIN(seek_point, 255)); + } + + avio_seek(s->pb, 0, SEEK_END); +} + static int mp3_write_trailer(struct AVFormatContext *s) { uint8_t buf[ID3v1_TAG_SIZE]; MP3Context *mp3 = s->priv_data; - if (mp3 && mp3->pics_to_write) { + if (mp3->pics_to_write) { av_log(s, AV_LOG_WARNING, "No packets were sent for some of the " "attached pictures.\n"); mp3_queue_flush(s); } /* write the id3v1 tag */ - if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) { + if (mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) { avio_write(s->pb, buf, ID3v1_TAG_SIZE); } - /* write number of frames */ - if (mp3 && mp3->nb_frames_offset) { - avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET); - avio_wb32(s->pb, s->streams[mp3->audio_stream_idx]->nb_frames); - avio_seek(s->pb, 0, SEEK_END); - } - - avio_flush(s->pb); + if (mp3->xing_offset) + mp3_update_xing(s); return 0; } @@ -209,7 +310,6 @@ AVOutputFormat ff_mp2_muxer = { .audio_codec = AV_CODEC_ID_MP2, .video_codec = AV_CODEC_ID_NONE, .write_packet = ff_raw_write_packet, - .write_trailer = mp3_write_trailer, .flags = AVFMT_NOTIMESTAMPS, }; #endif @@ -251,7 +351,7 @@ static int mp3_write_packet(AVFormatContext *s, AVPacket *pkt) mp3->queue = pktl; mp3->queue_end = pktl; } else - return ff_raw_write_packet(s, pkt); + return mp3_write_audio_packet(s, pkt); } else { int ret; -- cgit v1.2.3