@@ -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

@@ -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;

 }