libavformat/flacenc.c

   1 /*
   2  * raw FLAC muxer
   3  * Copyright (c) 2006-2009 Justin Ruggles
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * Libav is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavcodec/flac.h"
  23 #include "avformat.h"
  24 #include "flacenc.h"
  25 #include "vorbiscomment.h"
  26 #include "libavcodec/bytestream.h"
  27
  28
  29 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,
  30                                     int last_block)
  31 {
  32     avio_w8(pb, last_block ? 0x81 : 0x01);
  33     avio_wb24(pb, n_padding_bytes);
  34     while (n_padding_bytes > 0) {
  35         avio_w8(pb, 0);
  36         n_padding_bytes--;
  37     }
  38     return 0;
  39 }
  40
  41 static int flac_write_block_comment(AVIOContext *pb, AVDictionary **m,
  42                                     int last_block, int bitexact)
  43 {
  44     const char *vendor = bitexact ? "Libav" : LIBAVFORMAT_IDENT;
  45     unsigned int len, count;
  46     uint8_t *p, *p0;
  47
  48     ff_metadata_conv(m, ff_vorbiscomment_metadata_conv, NULL);
  49
  50     len = ff_vorbiscomment_length(*m, vendor, &count);
  51     p0 = av_malloc(len+4);
  52     if (!p0)
  53         return AVERROR(ENOMEM);
  54     p = p0;
  55
  56     bytestream_put_byte(&p, last_block ? 0x84 : 0x04);
  57     bytestream_put_be24(&p, len);
  58     ff_vorbiscomment_write(&p, m, vendor, count);
  59
  60     avio_write(pb, p0, len+4);
  61     av_freep(&p0);
  62     p = NULL;
  63
  64     return 0;
  65 }
  66
  67 static int flac_write_header(struct AVFormatContext *s)
  68 {
  69     int ret;
  70     AVCodecContext *codec = s->streams[0]->codec;
  71
  72     ret = ff_flac_write_header(s->pb, codec, 0);
  73     if (ret)
  74         return ret;
  75
  76     ret = flac_write_block_comment(s->pb, &s->metadata, 0,
  77                                    codec->flags & CODEC_FLAG_BITEXACT);
  78     if (ret)
  79         return ret;
  80
  81     /* The command line flac encoder defaults to placing a seekpoint
  82      * every 10s.  So one might add padding to allow that later
  83      * but there seems to be no simple way to get the duration here.
  84      * So let's try the flac default of 8192 bytes */
  85     flac_write_block_padding(s->pb, 8192, 1);
  86
  87     return ret;
  88 }
  89
  90 static int flac_write_trailer(struct AVFormatContext *s)
  91 {
  92     AVIOContext *pb = s->pb;
  93     uint8_t *streaminfo;
  94     enum FLACExtradataFormat format;
  95     int64_t file_size;
  96
  97     if (!avpriv_flac_is_extradata_valid(s->streams[0]->codec, &format, &streaminfo))
  98         return -1;
  99
 100     if (pb->seekable) {
 101         /* rewrite the STREAMINFO header block data */
 102         file_size = avio_tell(pb);
 103         avio_seek(pb, 8, SEEK_SET);
 104         avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
 105         avio_seek(pb, file_size, SEEK_SET);
 106         avio_flush(pb);
 107     } else {
 108         av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
 109     }
 110     return 0;
 111 }
 112
 113 static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)
 114 {
 115     avio_write(s->pb, pkt->data, pkt->size);
 116     avio_flush(s->pb);
 117     return 0;
 118 }
 119
 120 AVOutputFormat ff_flac_muxer = {
 121     .name              = "flac",
 122     .long_name         = NULL_IF_CONFIG_SMALL("raw FLAC"),
 123     .mime_type         = "audio/x-flac",
 124     .extensions        = "flac",
 125     .audio_codec       = AV_CODEC_ID_FLAC,
 126     .video_codec       = AV_CODEC_ID_NONE,
 127     .write_header      = flac_write_header,
 128     .write_packet      = flac_write_packet,
 129     .write_trailer     = flac_write_trailer,
 130     .flags             = AVFMT_NOTIMESTAMPS,
 131 };