libavformat/aeaenc.c

   1 /*
   2  * MD STUDIO audio muxer
   3  *
   4  * Copyright (c) 2024 asivery
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "avformat.h"
  24 #include "avio_internal.h"
  25 #include "rawenc.h"
  26 #include "mux.h"
  27
  28 static int aea_write_header(AVFormatContext *s)
  29 {
  30     const AVDictionaryEntry *title_entry;
  31     size_t title_length = 0;
  32     AVStream *st = s->streams[0];
  33
  34     if (st->codecpar->ch_layout.nb_channels != 1 && st->codecpar->ch_layout.nb_channels != 2) {
  35         av_log(s, AV_LOG_ERROR, "Only maximum 2 channels are supported in the audio"
  36                " stream, %d channels were found.\n", st->codecpar->ch_layout.nb_channels);
  37         return AVERROR(EINVAL);
  38     }
  39
  40     if (st->codecpar->sample_rate != 44100) {
  41         av_log(s, AV_LOG_ERROR, "Invalid sample rate (%d) AEA only supports 44.1kHz.\n", st->codecpar->sample_rate);
  42         return AVERROR(EINVAL);
  43     }
  44
  45     /* Write magic */
  46     avio_wl32(s->pb, 2048);
  47
  48     /* Write AEA title */
  49     title_entry = av_dict_get(st->metadata, "title", NULL, 0);
  50     if (title_entry) {
  51         const char *title_contents = title_entry->value;
  52         title_length = strlen(title_contents);
  53         if (title_length > 256) {
  54             av_log(s, AV_LOG_WARNING, "Title too long, truncated to 256 bytes.\n");
  55             title_length = 256;
  56         }
  57         avio_write(s->pb, title_contents, title_length);
  58     }
  59
  60     ffio_fill(s->pb, 0, 256 - title_length);
  61
  62     /* Write number of frames (zero at header-writing time, will seek later), number of channels */
  63     avio_wl32(s->pb, 0);
  64     avio_w8(s->pb, st->codecpar->ch_layout.nb_channels);
  65     avio_w8(s->pb, 0);
  66
  67     /* Pad the header to 2048 bytes */
  68     ffio_fill(s->pb, 0, 1782);
  69
  70     return 0;
  71 }
  72
  73 static int aea_write_trailer(struct AVFormatContext *s)
  74 {
  75     int64_t total_blocks;
  76     AVIOContext *pb = s->pb;
  77     AVStream *st = s->streams[0];
  78     if (pb->seekable & AVIO_SEEKABLE_NORMAL) {
  79         /* Seek to rewrite the block count. */
  80         avio_seek(pb, 260, SEEK_SET);
  81         total_blocks = st->nb_frames * st->codecpar->ch_layout.nb_channels;
  82         if (total_blocks > UINT32_MAX) {
  83             av_log(s, AV_LOG_WARNING, "Too many frames in the file to properly encode the header (%"PRId64")."
  84                    " Block count in the header will be truncated.\n", total_blocks);
  85             total_blocks = UINT32_MAX;
  86         }
  87         avio_wl32(pb, total_blocks);
  88     } else {
  89         av_log(s, AV_LOG_WARNING, "Unable to rewrite AEA header.\n");
  90     }
  91
  92     return 0;
  93 }
  94
  95 const FFOutputFormat ff_aea_muxer = {
  96     .p.name           = "aea",
  97     .p.long_name      = NULL_IF_CONFIG_SMALL("MD STUDIO audio"),
  98     .p.extensions     = "aea",
  99     .p.audio_codec    = AV_CODEC_ID_ATRAC1,
 100     .p.video_codec    = AV_CODEC_ID_NONE,
 101     .p.subtitle_codec = AV_CODEC_ID_NONE,
 102
 103     .flags_internal   = FF_OFMT_FLAG_MAX_ONE_OF_EACH |
 104                         FF_OFMT_FLAG_ONLY_DEFAULT_CODECS,
 105     .write_header     = aea_write_header,
 106     .write_packet     = ff_raw_write_packet,
 107     .write_trailer    = aea_write_trailer,
 108 };