[FFmpeg-cvslog] mp3enc: write full LAME frame
Anton Khirnov
git at videolan.org
Fri Oct 24 16:20:53 CEST 2014
ffmpeg | branch: master | Anton Khirnov <anton at khirnov.net> | Sat Apr 12 15:20:57 2014 +0200| [ef363ebd596da18f889a7d4845023a23dfac84c9] | committer: Anton Khirnov
mp3enc: write full LAME frame
Most importantly, it contains the encoder delay and replaygain info.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ef363ebd596da18f889a7d4845023a23dfac84c9
---
doc/muxers.texi | 3 +-
libavformat/mp3enc.c | 160 +++++++++++++++++++++++++++++++++++++++-----------
2 files changed, 129 insertions(+), 34 deletions(-)
diff --git a/doc/muxers.texi b/doc/muxers.texi
index bf4a66f..6b6e823 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -370,7 +370,8 @@ to provide the pictures as soon as possible to avoid excessive buffering.
A Xing/LAME frame right after the ID3v2 header (if present). It is enabled by
default, but will be written only if the output is seekable. The
@code{write_xing} private option can be used to disable it. The frame contains
-various information that may be useful to the decoder, like the audio duration.
+various information that may be useful to the decoder, like the audio duration
+or encoder delay.
@item
A legacy ID3v1 tag at the end of the file (disabled by default). It may be
diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c
index 476d7f7..bb96039 100644
--- a/libavformat/mp3enc.c
+++ b/libavformat/mp3enc.c
@@ -32,6 +32,9 @@
#include "libavutil/opt.h"
#include "libavutil/dict.h"
#include "libavutil/avassert.h"
+#include "libavutil/crc.h"
+#include "libavutil/mathematics.h"
+#include "libavutil/replaygain.h"
static int id3v1_set_string(AVFormatContext *s, const char *key,
uint8_t *buf, int buf_size)
@@ -76,8 +79,8 @@ static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
#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)
+// size of the XING/LAME data, starting from the Xing tag
+#define XING_SIZE 156
typedef struct MP3Context {
const AVClass *class;
@@ -87,7 +90,18 @@ typedef struct MP3Context {
int write_xing;
/* xing header */
- int64_t xing_offset;
+ // a buffer containing the whole XING/LAME frame
+ uint8_t *xing_frame;
+ int xing_frame_size;
+
+ AVCRC audio_crc; // CRC of the audio data
+ uint32_t audio_size; // total size of the audio data
+
+ // offset of the XING/LAME frame in the file
+ int64_t xing_frame_offset;
+ // offset of the XING/INFO tag in the frame
+ int xing_offset;
+
int32_t frames;
int32_t size;
uint32_t want;
@@ -115,13 +129,15 @@ static void mp3_write_xing(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
AVCodecContext *codec = s->streams[mp3->audio_stream_idx]->codec;
+ AVDictionaryEntry *enc = av_dict_get(s->streams[mp3->audio_stream_idx]->metadata, "encoder", NULL, 0);
+ AVIOContext *dyn_ctx;
int32_t header;
MPADecodeHeader mpah;
int srate_idx, i, channels;
int bitrate_idx;
int best_bitrate_idx;
int best_bitrate_error = INT_MAX;
- int xing_offset;
+ int ret;
int ver = 0;
int lsf, bytes_needed;
@@ -161,14 +177,8 @@ static void mp3_write_xing(AVFormatContext *s)
lsf = !((header & (1 << 20) && header & (1 << 19)));
- xing_offset = xing_offtbl[ver != 3][channels == 1];
- bytes_needed = 4 // header
- + xing_offset
- + 4 // xing tag
- + 4 // frames/size/toc flags
- + 4 // frames
- + 4 // size
- + XING_TOC_SIZE; // toc
+ mp3->xing_offset = xing_offtbl[ver != 3][channels == 1] + 4;
+ bytes_needed = mp3->xing_offset + XING_SIZE;
for (bitrate_idx = 1; bitrate_idx < 15; bitrate_idx++) {
int bit_rate = 1000 * avpriv_mpa_bitrate_tab[lsf][3 - 1][bitrate_idx];
@@ -192,28 +202,72 @@ static void mp3_write_xing(AVFormatContext *s)
header &= ~mask;
}
- avio_wb32(s->pb, header);
+ ret = avio_open_dyn_buf(&dyn_ctx);
+ if (ret < 0)
+ return;
+
+ avio_wb32(dyn_ctx, header);
avpriv_mpegaudio_decode_header(&mpah, header);
- av_assert0(mpah.frame_size >= XING_MAX_SIZE);
+ av_assert0(mpah.frame_size >= bytes_needed);
- ffio_fill(s->pb, 0, xing_offset);
- mp3->xing_offset = avio_tell(s->pb);
- ffio_wfourcc(s->pb, "Xing");
- avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames / size / TOC
+ ffio_fill(dyn_ctx, 0, mp3->xing_offset - 4);
+ ffio_wfourcc(dyn_ctx, "Xing");
+ avio_wb32(dyn_ctx, 0x01 | 0x02 | 0x04 | 0x08); // frames / size / TOC / vbr scale
mp3->size = mpah.frame_size;
mp3->want = 1;
- avio_wb32(s->pb, 0); // frames
- avio_wb32(s->pb, 0); // size
+ avio_wb32(dyn_ctx, 0); // frames
+ avio_wb32(dyn_ctx, 0); // size
// TOC
for (i = 0; i < XING_TOC_SIZE; i++)
- avio_w8(s->pb, 255 * i / XING_TOC_SIZE);
+ avio_w8(dyn_ctx, 255 * i / XING_TOC_SIZE);
+
+ // vbr quality
+ // we write it, because some (broken) tools always expect it to be present
+ avio_wb32(dyn_ctx, 0);
+
+ // encoder short version string
+ if (enc) {
+ uint8_t encoder_str[9] = { 0 };
+ memcpy(encoder_str, enc->value, FFMIN(strlen(enc->value), sizeof(encoder_str)));
+ avio_write(dyn_ctx, encoder_str, sizeof(encoder_str));
+ } else
+ ffio_fill(dyn_ctx, 0, 9);
+
+ avio_w8(dyn_ctx, 0); // tag revision 0 / unknown vbr method
+ avio_w8(dyn_ctx, 0); // unknown lowpass filter value
+ ffio_fill(dyn_ctx, 0, 8); // empty replaygain fields
+ avio_w8(dyn_ctx, 0); // unknown encoding flags
+ avio_w8(dyn_ctx, 0); // unknown abr/minimal bitrate
+
+ // encoder delay
+ if (codec->initial_padding >= 1 << 12) {
+ av_log(s, AV_LOG_WARNING, "Too many samples of initial padding.\n");
+ avio_wb24(dyn_ctx, 0);
+ } else {
+ avio_wb24(dyn_ctx, codec->initial_padding << 12);
+ }
+
+ avio_w8(dyn_ctx, 0); // misc
+ avio_w8(dyn_ctx, 0); // mp3gain
+ avio_wb16(dyn_ctx, 0); // preset
+
+ // audio length and CRCs (will be updated later)
+ avio_wb32(dyn_ctx, 0); // music length
+ avio_wb16(dyn_ctx, 0); // music crc
+ avio_wb16(dyn_ctx, 0); // tag crc
- ffio_fill(s->pb, 0, mpah.frame_size - bytes_needed);
+ ffio_fill(dyn_ctx, 0, mpah.frame_size - bytes_needed);
+
+ mp3->xing_frame_size = avio_close_dyn_buf(dyn_ctx, &mp3->xing_frame);
+ mp3->xing_frame_offset = avio_tell(s->pb);
+ avio_write(s->pb, mp3->xing_frame, mp3->xing_frame_size);
+
+ mp3->audio_size = mp3->xing_frame_size;
}
/*
@@ -264,6 +318,12 @@ static int mp3_write_audio_packet(AVFormatContext *s, AVPacket *pkt)
}
mp3_xing_add_frame(mp3, pkt);
+
+ if (mp3->xing_offset) {
+ mp3->audio_size += pkt->size;
+ mp3->audio_crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI_LE),
+ mp3->audio_crc, pkt->data, pkt->size);
+ }
}
return ff_raw_write_packet(s, pkt);
@@ -292,26 +352,58 @@ static int mp3_queue_flush(AVFormatContext *s)
static void mp3_update_xing(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
- int i;
+ AVReplayGain *rg;
+ uint16_t tag_crc;
+ uint8_t *toc;
+ int i, rg_size;
/* 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);
+ if (!mp3->has_variable_bitrate)
+ AV_WL32(mp3->xing_frame + mp3->xing_offset, MKTAG('I', 'n', 'f', 'o'));
- avio_w8(s->pb, 0); // first toc entry has to be zero.
+ AV_WB32(mp3->xing_frame + mp3->xing_offset + 8, mp3->frames);
+ AV_WB32(mp3->xing_frame + mp3->xing_offset + 12, mp3->size);
+ toc = mp3->xing_frame + mp3->xing_offset + 16;
+ toc[0] = 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));
+ toc[i] = FFMIN(seek_point, 255);
+ }
+
+ /* write replaygain */
+ rg = (AVReplayGain*)av_stream_get_side_data(s->streams[0], AV_PKT_DATA_REPLAYGAIN,
+ &rg_size);
+ if (rg && rg_size >= sizeof(*rg)) {
+ uint16_t val;
+
+ AV_WB32(mp3->xing_frame + mp3->xing_offset + 131,
+ av_rescale(rg->track_peak, 1 << 23, 100000));
+
+ if (rg->track_gain != INT32_MIN) {
+ val = FFABS(rg->track_gain / 10000) & ((1 << 9) - 1);
+ val |= (rg->track_gain < 0) << 9;
+ val |= 1 << 13;
+ AV_WB16(mp3->xing_frame + mp3->xing_offset + 135, val);
+ }
+
+ if (rg->album_gain != INT32_MIN) {
+ val = FFABS(rg->album_gain / 10000) & ((1 << 9) - 1);
+ val |= (rg->album_gain < 0) << 9;
+ val |= 1 << 14;
+ AV_WB16(mp3->xing_frame + mp3->xing_offset + 137, val);
+ }
}
+ AV_WB32(mp3->xing_frame + mp3->xing_offset + XING_SIZE - 8, mp3->audio_size);
+ AV_WB16(mp3->xing_frame + mp3->xing_offset + XING_SIZE - 4, mp3->audio_crc);
+
+ tag_crc = av_crc(av_crc_get_table(AV_CRC_16_ANSI_LE), 0, mp3->xing_frame, 190);
+ AV_WB16(mp3->xing_frame + mp3->xing_offset + XING_SIZE - 2, tag_crc);
+
+ avio_seek(s->pb, mp3->xing_frame_offset, SEEK_SET);
+ avio_write(s->pb, mp3->xing_frame, mp3->xing_frame_size);
avio_seek(s->pb, 0, SEEK_END);
}
@@ -334,6 +426,8 @@ static int mp3_write_trailer(struct AVFormatContext *s)
if (mp3->xing_offset)
mp3_update_xing(s);
+ av_freep(&mp3->xing_frame);
+
return 0;
}
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