[FFmpeg-cvslog] Split mp3 demuxer and muxer into separate files.

Anton Khirnov git
Fri Jan 21 20:40:04 CET 2011


ffmpeg | branch: master | Anton Khirnov <anton at khirnov.net> | Fri Jan 21 13:53:46 2011 +0000| [baa69f8a8498e6bfde5b8de1bece4825fa0d784b] | committer: Michael Niedermayer

Split mp3 demuxer and muxer into separate files.

Signed-off-by: Mans Rullgard <mans at mansr.com>
(cherry picked from commit d08928bbea2b495596c2d3bc7df3cfb3e3b2b7e3)

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=baa69f8a8498e6bfde5b8de1bece4825fa0d784b
---

 libavformat/Makefile |    6 +-
 libavformat/mp3.c    |  368 --------------------------------------------------
 libavformat/mp3dec.c |  192 ++++++++++++++++++++++++++
 libavformat/mp3enc.c |  194 ++++++++++++++++++++++++++
 4 files changed, 389 insertions(+), 371 deletions(-)

diff --git a/libavformat/Makefile b/libavformat/Makefile
index d3c849a..dd13bb4 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -129,9 +129,9 @@ OBJS-$(CONFIG_MMF_DEMUXER)               += mmf.o pcm.o
 OBJS-$(CONFIG_MMF_MUXER)                 += mmf.o riff.o
 OBJS-$(CONFIG_MOV_DEMUXER)               += mov.o riff.o isom.o
 OBJS-$(CONFIG_MOV_MUXER)                 += movenc.o riff.o isom.o avc.o movenchint.o
-OBJS-$(CONFIG_MP2_MUXER)                 += mp3.o
-OBJS-$(CONFIG_MP3_DEMUXER)               += mp3.o
-OBJS-$(CONFIG_MP3_MUXER)                 += mp3.o
+OBJS-$(CONFIG_MP2_MUXER)                 += mp3enc.o
+OBJS-$(CONFIG_MP3_DEMUXER)               += mp3dec.o
+OBJS-$(CONFIG_MP3_MUXER)                 += mp3enc.o
 OBJS-$(CONFIG_MPC_DEMUXER)               += mpc.o apetag.o
 OBJS-$(CONFIG_MPC8_DEMUXER)              += mpc8.o
 OBJS-$(CONFIG_MPEG1SYSTEM_MUXER)         += mpegenc.o
diff --git a/libavformat/mp3.c b/libavformat/mp3.c
deleted file mode 100644
index e70a120..0000000
--- a/libavformat/mp3.c
+++ /dev/null
@@ -1,368 +0,0 @@
-/*
- * MP3 muxer and demuxer
- * Copyright (c) 2003 Fabrice Bellard
- *
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <strings.h>
-#include "libavutil/avstring.h"
-#include "libavutil/intreadwrite.h"
-#include "avformat.h"
-#include "id3v2.h"
-#include "id3v1.h"
-
-#if CONFIG_MP3_DEMUXER
-
-#include "libavcodec/mpegaudio.h"
-#include "libavcodec/mpegaudiodecheader.h"
-
-/* mp3 read */
-
-static int mp3_read_probe(AVProbeData *p)
-{
-    int max_frames, first_frames = 0;
-    int fsize, frames, sample_rate;
-    uint32_t header;
-    uint8_t *buf, *buf0, *buf2, *end;
-    AVCodecContext avctx;
-
-    buf0 = p->buf;
-    end = p->buf + p->buf_size - sizeof(uint32_t);
-    while(buf0 < end && !*buf0)
-        buf0++;
-
-    max_frames = 0;
-    buf = buf0;
-
-    for(; buf < end; buf= buf2+1) {
-        buf2 = buf;
-
-        for(frames = 0; buf2 < end; frames++) {
-            header = AV_RB32(buf2);
-            fsize = ff_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
-            if(fsize < 0)
-                break;
-            buf2 += fsize;
-        }
-        max_frames = FFMAX(max_frames, frames);
-        if(buf == buf0)
-            first_frames= frames;
-    }
-    // keep this in sync with ac3 probe, both need to avoid
-    // issues with MPEG-files!
-    if   (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
-    else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
-    else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
-    else if(max_frames>=1) return 1;
-    else                   return 0;
-//mpegps_mp3_unrecognized_format.mpg has max_frames=3
-}
-
-/**
- * Try to find Xing/Info/VBRI tags and compute duration from info therein
- */
-static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
-{
-    uint32_t v, spf;
-    unsigned frames = 0; /* Total number of frames in file */
-    unsigned size = 0; /* Total number of bytes in the stream */
-    const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
-    MPADecodeHeader c;
-    int vbrtag_size = 0;
-
-    v = get_be32(s->pb);
-    if(ff_mpa_check_header(v) < 0)
-      return -1;
-
-    if (ff_mpegaudio_decode_header(&c, v) == 0)
-        vbrtag_size = c.frame_size;
-    if(c.layer != 3)
-        return -1;
-
-    /* Check for Xing / Info tag */
-    url_fseek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
-    v = get_be32(s->pb);
-    if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
-        v = get_be32(s->pb);
-        if(v & 0x1)
-            frames = get_be32(s->pb);
-        if(v & 0x2)
-            size = get_be32(s->pb);
-    }
-
-    /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
-    url_fseek(s->pb, base + 4 + 32, SEEK_SET);
-    v = get_be32(s->pb);
-    if(v == MKBETAG('V', 'B', 'R', 'I')) {
-        /* Check tag version */
-        if(get_be16(s->pb) == 1) {
-            /* skip delay and quality */
-            url_fseek(s->pb, 4, SEEK_CUR);
-            frames = get_be32(s->pb);
-            size = get_be32(s->pb);
-        }
-    }
-
-    if(!frames && !size)
-        return -1;
-
-    /* Skip the vbr tag frame */
-    url_fseek(s->pb, base + vbrtag_size, SEEK_SET);
-
-    spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
-    if(frames)
-        st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
-                                    st->time_base);
-    if(size && frames)
-        st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
-
-    return 0;
-}
-
-static int mp3_read_header(AVFormatContext *s,
-                           AVFormatParameters *ap)
-{
-    AVStream *st;
-    int64_t off;
-
-    st = av_new_stream(s, 0);
-    if (!st)
-        return AVERROR(ENOMEM);
-
-    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
-    st->codec->codec_id = CODEC_ID_MP3;
-    st->need_parsing = AVSTREAM_PARSE_FULL;
-    st->start_time = 0;
-
-    // lcm of all mp3 sample rates
-    av_set_pts_info(st, 64, 1, 14112000);
-
-    off = url_ftell(s->pb);
-
-    if (!av_metadata_get(s->metadata, "", NULL, AV_METADATA_IGNORE_SUFFIX))
-        ff_id3v1_read(s);
-
-    if (mp3_parse_vbr_tags(s, st, off) < 0)
-        url_fseek(s->pb, off, SEEK_SET);
-
-    /* the parameters will be extracted from the compressed bitstream */
-    return 0;
-}
-
-#define MP3_PACKET_SIZE 1024
-
-static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
-{
-    int ret, size;
-    //    AVStream *st = s->streams[0];
-
-    size= MP3_PACKET_SIZE;
-
-    ret= av_get_packet(s->pb, pkt, size);
-
-    pkt->stream_index = 0;
-    if (ret <= 0) {
-        return AVERROR(EIO);
-    }
-    /* note: we need to modify the packet size here to handle the last
-       packet */
-    pkt->size = ret;
-    return ret;
-}
-
-AVInputFormat mp3_demuxer = {
-    "mp3",
-    NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),
-    0,
-    mp3_read_probe,
-    mp3_read_header,
-    mp3_read_packet,
-    .flags= AVFMT_GENERIC_INDEX,
-    .extensions = "mp2,mp3,m2a", /* XXX: use probe */
-};
-#endif
-
-#if CONFIG_MP2_MUXER || CONFIG_MP3_MUXER
-static int id3v1_set_string(AVFormatContext *s, const char *key,
-                            uint8_t *buf, int buf_size)
-{
-    AVMetadataTag *tag;
-    if ((tag = av_metadata_get(s->metadata, key, NULL, 0)))
-        strncpy(buf, tag->value, buf_size);
-    return !!tag;
-}
-
-static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
-{
-    AVMetadataTag *tag;
-    int i, count = 0;
-
-    memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
-    buf[0] = 'T';
-    buf[1] = 'A';
-    buf[2] = 'G';
-    count += id3v1_set_string(s, "TIT2",    buf +  3, 30);       //title
-    count += id3v1_set_string(s, "TPE1",    buf + 33, 30);       //author|artist
-    count += id3v1_set_string(s, "TALB",    buf + 63, 30);       //album
-    count += id3v1_set_string(s, "TDRL",    buf + 93,  4);       //date
-    count += id3v1_set_string(s, "comment", buf + 97, 30);
-    if ((tag = av_metadata_get(s->metadata, "TRCK", NULL, 0))) { //track
-        buf[125] = 0;
-        buf[126] = atoi(tag->value);
-        count++;
-    }
-    buf[127] = 0xFF; /* default to unknown genre */
-    if ((tag = av_metadata_get(s->metadata, "TCON", NULL, 0))) { //genre
-        for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
-            if (!strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
-                buf[127] = i;
-                count++;
-                break;
-            }
-        }
-    }
-    return count;
-}
-
-/* simple formats */
-
-static void id3v2_put_size(AVFormatContext *s, int size)
-{
-    put_byte(s->pb, size >> 21 & 0x7f);
-    put_byte(s->pb, size >> 14 & 0x7f);
-    put_byte(s->pb, size >> 7  & 0x7f);
-    put_byte(s->pb, size       & 0x7f);
-}
-
-static void id3v2_put_ttag(AVFormatContext *s, const char *buf, int len,
-                           uint32_t tag)
-{
-    put_be32(s->pb, tag);
-    id3v2_put_size(s, len + 1);
-    put_be16(s->pb, 0);
-    put_byte(s->pb, 3); /* UTF-8 */
-    put_buffer(s->pb, buf, len);
-}
-
-
-static int mp3_write_packet(struct AVFormatContext *s, AVPacket *pkt)
-{
-    put_buffer(s->pb, pkt->data, pkt->size);
-    put_flush_packet(s->pb);
-    return 0;
-}
-
-static int mp3_write_trailer(struct AVFormatContext *s)
-{
-    uint8_t buf[ID3v1_TAG_SIZE];
-
-    /* write the id3v1 tag */
-    if (id3v1_create_tag(s, buf) > 0) {
-        put_buffer(s->pb, buf, ID3v1_TAG_SIZE);
-        put_flush_packet(s->pb);
-    }
-    return 0;
-}
-#endif /* CONFIG_MP2_MUXER || CONFIG_MP3_MUXER */
-
-#if CONFIG_MP2_MUXER
-AVOutputFormat mp2_muxer = {
-    "mp2",
-    NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
-    "audio/x-mpeg",
-    "mp2,m2a",
-    0,
-    CODEC_ID_MP2,
-    CODEC_ID_NONE,
-    NULL,
-    mp3_write_packet,
-    mp3_write_trailer,
-};
-#endif
-
-#if CONFIG_MP3_MUXER
-/**
- * Write an ID3v2.4 header at beginning of stream
- */
-
-static int mp3_write_header(struct AVFormatContext *s)
-{
-    AVMetadataTag *t = NULL;
-    int totlen = 0;
-    int64_t size_pos, cur_pos;
-
-    put_be32(s->pb, MKBETAG('I', 'D', '3', 0x04)); /* ID3v2.4 */
-    put_byte(s->pb, 0);
-    put_byte(s->pb, 0); /* flags */
-
-    /* reserve space for size */
-    size_pos = url_ftell(s->pb);
-    put_be32(s->pb, 0);
-
-    ff_metadata_conv(&s->metadata, ff_id3v2_metadata_conv, NULL);
-    while ((t = av_metadata_get(s->metadata, "", t, AV_METADATA_IGNORE_SUFFIX))) {
-        uint32_t tag = 0;
-
-        if (t->key[0] == 'T' && strlen(t->key) == 4) {
-            int i;
-            for (i = 0; *ff_id3v2_tags[i]; i++)
-                if (AV_RB32(t->key) == AV_RB32(ff_id3v2_tags[i])) {
-                    int len = strlen(t->value);
-                    tag = AV_RB32(t->key);
-                    totlen += len + ID3v2_HEADER_SIZE + 2;
-                    id3v2_put_ttag(s, t->value, len + 1, tag);
-                    break;
-                }
-        }
-
-        if (!tag) { /* unknown tag, write as TXXX frame */
-            int   len = strlen(t->key), len1 = strlen(t->value);
-            char *buf = av_malloc(len + len1 + 2);
-            if (!buf)
-                return AVERROR(ENOMEM);
-            tag = MKBETAG('T', 'X', 'X', 'X');
-            strcpy(buf,           t->key);
-            strcpy(buf + len + 1, t->value);
-            id3v2_put_ttag(s, buf, len + len1 + 2, tag);
-            totlen += len + len1 + ID3v2_HEADER_SIZE + 3;
-            av_free(buf);
-        }
-    }
-
-    cur_pos = url_ftell(s->pb);
-    url_fseek(s->pb, size_pos, SEEK_SET);
-    id3v2_put_size(s, totlen);
-    url_fseek(s->pb, cur_pos, SEEK_SET);
-
-    return 0;
-}
-
-AVOutputFormat mp3_muxer = {
-    "mp3",
-    NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
-    "audio/x-mpeg",
-    "mp3",
-    0,
-    CODEC_ID_MP3,
-    CODEC_ID_NONE,
-    mp3_write_header,
-    mp3_write_packet,
-    mp3_write_trailer,
-    AVFMT_NOTIMESTAMPS,
-};
-#endif
diff --git a/libavformat/mp3dec.c b/libavformat/mp3dec.c
new file mode 100644
index 0000000..ab6aabe
--- /dev/null
+++ b/libavformat/mp3dec.c
@@ -0,0 +1,192 @@
+/*
+ * MP3 demuxer
+ * Copyright (c) 2003 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/avstring.h"
+#include "libavutil/intreadwrite.h"
+#include "avformat.h"
+#include "id3v2.h"
+#include "id3v1.h"
+#include "libavcodec/mpegaudiodecheader.h"
+
+/* mp3 read */
+
+static int mp3_read_probe(AVProbeData *p)
+{
+    int max_frames, first_frames = 0;
+    int fsize, frames, sample_rate;
+    uint32_t header;
+    uint8_t *buf, *buf0, *buf2, *end;
+    AVCodecContext avctx;
+
+    buf0 = p->buf;
+    end = p->buf + p->buf_size - sizeof(uint32_t);
+    while(buf0 < end && !*buf0)
+        buf0++;
+
+    max_frames = 0;
+    buf = buf0;
+
+    for(; buf < end; buf= buf2+1) {
+        buf2 = buf;
+
+        for(frames = 0; buf2 < end; frames++) {
+            header = AV_RB32(buf2);
+            fsize = ff_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
+            if(fsize < 0)
+                break;
+            buf2 += fsize;
+        }
+        max_frames = FFMAX(max_frames, frames);
+        if(buf == buf0)
+            first_frames= frames;
+    }
+    // keep this in sync with ac3 probe, both need to avoid
+    // issues with MPEG-files!
+    if   (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
+    else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
+    else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
+    else if(max_frames>=1) return 1;
+    else                   return 0;
+//mpegps_mp3_unrecognized_format.mpg has max_frames=3
+}
+
+/**
+ * Try to find Xing/Info/VBRI tags and compute duration from info therein
+ */
+static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
+{
+    uint32_t v, spf;
+    unsigned frames = 0; /* Total number of frames in file */
+    unsigned size = 0; /* Total number of bytes in the stream */
+    const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
+    MPADecodeHeader c;
+    int vbrtag_size = 0;
+
+    v = get_be32(s->pb);
+    if(ff_mpa_check_header(v) < 0)
+      return -1;
+
+    if (ff_mpegaudio_decode_header(&c, v) == 0)
+        vbrtag_size = c.frame_size;
+    if(c.layer != 3)
+        return -1;
+
+    /* Check for Xing / Info tag */
+    url_fseek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
+    v = get_be32(s->pb);
+    if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
+        v = get_be32(s->pb);
+        if(v & 0x1)
+            frames = get_be32(s->pb);
+        if(v & 0x2)
+            size = get_be32(s->pb);
+    }
+
+    /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
+    url_fseek(s->pb, base + 4 + 32, SEEK_SET);
+    v = get_be32(s->pb);
+    if(v == MKBETAG('V', 'B', 'R', 'I')) {
+        /* Check tag version */
+        if(get_be16(s->pb) == 1) {
+            /* skip delay and quality */
+            url_fseek(s->pb, 4, SEEK_CUR);
+            frames = get_be32(s->pb);
+            size = get_be32(s->pb);
+        }
+    }
+
+    if(!frames && !size)
+        return -1;
+
+    /* Skip the vbr tag frame */
+    url_fseek(s->pb, base + vbrtag_size, SEEK_SET);
+
+    spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
+    if(frames)
+        st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
+                                    st->time_base);
+    if(size && frames)
+        st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
+
+    return 0;
+}
+
+static int mp3_read_header(AVFormatContext *s,
+                           AVFormatParameters *ap)
+{
+    AVStream *st;
+    int64_t off;
+
+    st = av_new_stream(s, 0);
+    if (!st)
+        return AVERROR(ENOMEM);
+
+    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
+    st->codec->codec_id = CODEC_ID_MP3;
+    st->need_parsing = AVSTREAM_PARSE_FULL;
+    st->start_time = 0;
+
+    // lcm of all mp3 sample rates
+    av_set_pts_info(st, 64, 1, 14112000);
+
+    off = url_ftell(s->pb);
+
+    if (!av_metadata_get(s->metadata, "", NULL, AV_METADATA_IGNORE_SUFFIX))
+        ff_id3v1_read(s);
+
+    if (mp3_parse_vbr_tags(s, st, off) < 0)
+        url_fseek(s->pb, off, SEEK_SET);
+
+    /* the parameters will be extracted from the compressed bitstream */
+    return 0;
+}
+
+#define MP3_PACKET_SIZE 1024
+
+static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    int ret, size;
+    //    AVStream *st = s->streams[0];
+
+    size= MP3_PACKET_SIZE;
+
+    ret= av_get_packet(s->pb, pkt, size);
+
+    pkt->stream_index = 0;
+    if (ret <= 0) {
+        return AVERROR(EIO);
+    }
+    /* note: we need to modify the packet size here to handle the last
+       packet */
+    pkt->size = ret;
+    return ret;
+}
+
+AVInputFormat mp3_demuxer = {
+    "mp3",
+    NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),
+    0,
+    mp3_read_probe,
+    mp3_read_header,
+    mp3_read_packet,
+    .flags= AVFMT_GENERIC_INDEX,
+    .extensions = "mp2,mp3,m2a", /* XXX: use probe */
+};
diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c
new file mode 100644
index 0000000..b4fb876
--- /dev/null
+++ b/libavformat/mp3enc.c
@@ -0,0 +1,194 @@
+/*
+ * MP3 muxer
+ * Copyright (c) 2003 Fabrice Bellard
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <strings.h>
+#include "avformat.h"
+#include "id3v1.h"
+#include "id3v2.h"
+#include "libavutil/intreadwrite.h"
+
+static int id3v1_set_string(AVFormatContext *s, const char *key,
+                            uint8_t *buf, int buf_size)
+{
+    AVMetadataTag *tag;
+    if ((tag = av_metadata_get(s->metadata, key, NULL, 0)))
+        strncpy(buf, tag->value, buf_size);
+    return !!tag;
+}
+
+static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
+{
+    AVMetadataTag *tag;
+    int i, count = 0;
+
+    memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
+    buf[0] = 'T';
+    buf[1] = 'A';
+    buf[2] = 'G';
+    count += id3v1_set_string(s, "TIT2",    buf +  3, 30);       //title
+    count += id3v1_set_string(s, "TPE1",    buf + 33, 30);       //author|artist
+    count += id3v1_set_string(s, "TALB",    buf + 63, 30);       //album
+    count += id3v1_set_string(s, "TDRL",    buf + 93,  4);       //date
+    count += id3v1_set_string(s, "comment", buf + 97, 30);
+    if ((tag = av_metadata_get(s->metadata, "TRCK", NULL, 0))) { //track
+        buf[125] = 0;
+        buf[126] = atoi(tag->value);
+        count++;
+    }
+    buf[127] = 0xFF; /* default to unknown genre */
+    if ((tag = av_metadata_get(s->metadata, "TCON", NULL, 0))) { //genre
+        for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
+            if (!strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
+                buf[127] = i;
+                count++;
+                break;
+            }
+        }
+    }
+    return count;
+}
+
+/* simple formats */
+
+static void id3v2_put_size(AVFormatContext *s, int size)
+{
+    put_byte(s->pb, size >> 21 & 0x7f);
+    put_byte(s->pb, size >> 14 & 0x7f);
+    put_byte(s->pb, size >> 7  & 0x7f);
+    put_byte(s->pb, size       & 0x7f);
+}
+
+static void id3v2_put_ttag(AVFormatContext *s, const char *buf, int len,
+                           uint32_t tag)
+{
+    put_be32(s->pb, tag);
+    id3v2_put_size(s, len + 1);
+    put_be16(s->pb, 0);
+    put_byte(s->pb, 3); /* UTF-8 */
+    put_buffer(s->pb, buf, len);
+}
+
+
+static int mp3_write_packet(struct AVFormatContext *s, AVPacket *pkt)
+{
+    put_buffer(s->pb, pkt->data, pkt->size);
+    put_flush_packet(s->pb);
+    return 0;
+}
+
+static int mp3_write_trailer(struct AVFormatContext *s)
+{
+    uint8_t buf[ID3v1_TAG_SIZE];
+
+    /* write the id3v1 tag */
+    if (id3v1_create_tag(s, buf) > 0) {
+        put_buffer(s->pb, buf, ID3v1_TAG_SIZE);
+        put_flush_packet(s->pb);
+    }
+    return 0;
+}
+
+#if CONFIG_MP2_MUXER
+AVOutputFormat mp2_muxer = {
+    "mp2",
+    NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
+    "audio/x-mpeg",
+    "mp2,m2a",
+    0,
+    CODEC_ID_MP2,
+    CODEC_ID_NONE,
+    NULL,
+    mp3_write_packet,
+    mp3_write_trailer,
+};
+#endif
+
+#if CONFIG_MP3_MUXER
+/**
+ * Write an ID3v2.4 header at beginning of stream
+ */
+
+static int mp3_write_header(struct AVFormatContext *s)
+{
+    AVMetadataTag *t = NULL;
+    int totlen = 0;
+    int64_t size_pos, cur_pos;
+
+    put_be32(s->pb, MKBETAG('I', 'D', '3', 0x04)); /* ID3v2.4 */
+    put_byte(s->pb, 0);
+    put_byte(s->pb, 0); /* flags */
+
+    /* reserve space for size */
+    size_pos = url_ftell(s->pb);
+    put_be32(s->pb, 0);
+
+    ff_metadata_conv(&s->metadata, ff_id3v2_metadata_conv, NULL);
+    while ((t = av_metadata_get(s->metadata, "", t, AV_METADATA_IGNORE_SUFFIX))) {
+        uint32_t tag = 0;
+
+        if (t->key[0] == 'T' && strlen(t->key) == 4) {
+            int i;
+            for (i = 0; *ff_id3v2_tags[i]; i++)
+                if (AV_RB32(t->key) == AV_RB32(ff_id3v2_tags[i])) {
+                    int len = strlen(t->value);
+                    tag = AV_RB32(t->key);
+                    totlen += len + ID3v2_HEADER_SIZE + 2;
+                    id3v2_put_ttag(s, t->value, len + 1, tag);
+                    break;
+                }
+        }
+
+        if (!tag) { /* unknown tag, write as TXXX frame */
+            int   len = strlen(t->key), len1 = strlen(t->value);
+            char *buf = av_malloc(len + len1 + 2);
+            if (!buf)
+                return AVERROR(ENOMEM);
+            tag = MKBETAG('T', 'X', 'X', 'X');
+            strcpy(buf,           t->key);
+            strcpy(buf + len + 1, t->value);
+            id3v2_put_ttag(s, buf, len + len1 + 2, tag);
+            totlen += len + len1 + ID3v2_HEADER_SIZE + 3;
+            av_free(buf);
+        }
+    }
+
+    cur_pos = url_ftell(s->pb);
+    url_fseek(s->pb, size_pos, SEEK_SET);
+    id3v2_put_size(s, totlen);
+    url_fseek(s->pb, cur_pos, SEEK_SET);
+
+    return 0;
+}
+
+AVOutputFormat mp3_muxer = {
+    "mp3",
+    NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
+    "audio/x-mpeg",
+    "mp3",
+    0,
+    CODEC_ID_MP3,
+    CODEC_ID_NONE,
+    mp3_write_header,
+    mp3_write_packet,
+    mp3_write_trailer,
+    AVFMT_NOTIMESTAMPS,
+};
+#endif




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