text: /*
   * Raw FLAC demuxer
   * Copyright (c) 2001 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 "libavcodec/flac.h"
  #include "avformat.h"
  #include "flac_picture.h"
  #include "internal.h"
  #include "rawdec.h"
  #include "oggdec.h"
  #include "vorbiscomment.h"
  #include "replaygain.h"
  
  #define SEEKPOINT_SIZE 18
  
  typedef struct FLACDecContext {
      AVClass *class;
      int raw_packet_size;
      int found_seektable;
  } FLACDecContext;
  
  static void reset_index_position(int64_t metadata_head_size, AVStream *st)
  {
      /* the real seek index offset should be the size of metadata blocks with the offset in the frame blocks */
      int i;
      for(i=0; i<st->nb_index_entries; i++) {
          st->index_entries[i].pos += metadata_head_size;
      }
  }
  
  static int flac_read_header(AVFormatContext *s)
  {
      int ret, metadata_last=0, metadata_type, metadata_size, found_streaminfo=0;
      uint8_t header[4];
      uint8_t *buffer=NULL, *tmp=NULL;
      FLACDecContext *flac = s->priv_data;
      AVStream *st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
      st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
      st->codecpar->codec_id = AV_CODEC_ID_FLAC;
      st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
      /* the parameters will be extracted from the compressed bitstream */
  
      /* if fLaC marker is not found, assume there is no header */
      if (avio_rl32(s->pb) != MKTAG('f','L','a','C')) {
          avio_seek(s->pb, -4, SEEK_CUR);
          return 0;
      }
  
      /* process metadata blocks */
      while (!avio_feof(s->pb) && !metadata_last) {
          if (avio_read(s->pb, header, 4) != 4)
              return AVERROR(AVERROR_INVALIDDATA);
          flac_parse_block_header(header, &metadata_last, &metadata_type,
                                     &metadata_size);
          switch (metadata_type) {
          /* allocate and read metadata block for supported types */
          case FLAC_METADATA_TYPE_STREAMINFO:
          case FLAC_METADATA_TYPE_CUESHEET:
          case FLAC_METADATA_TYPE_PICTURE:
          case FLAC_METADATA_TYPE_VORBIS_COMMENT:
          case FLAC_METADATA_TYPE_SEEKTABLE:
              buffer = av_mallocz(metadata_size + AV_INPUT_BUFFER_PADDING_SIZE);
              if (!buffer) {
                  return AVERROR(ENOMEM);
              }
              if (avio_read(s->pb, buffer, metadata_size) != metadata_size) {
                  RETURN_ERROR(AVERROR(EIO));
              }
              break;
          /* skip metadata block for unsupported types */
          default:
              ret = avio_skip(s->pb, metadata_size);
              if (ret < 0)
                  return ret;
          }
  
          if (metadata_type == FLAC_METADATA_TYPE_STREAMINFO) {
              uint32_t samplerate;
              uint64_t samples;
  
              /* STREAMINFO can only occur once */
              if (found_streaminfo) {
                  RETURN_ERROR(AVERROR_INVALIDDATA);
              }
              if (metadata_size != FLAC_STREAMINFO_SIZE) {
                  RETURN_ERROR(AVERROR_INVALIDDATA);
              }
              found_streaminfo = 1;
              st->codecpar->extradata      = av_malloc(metadata_size + 8 + AV_INPUT_BUFFER_PADDING_SIZE);
              if (!st->codecpar->extradata) {
                RETURN_ERROR(AVERROR(ENOMEM));
              }
              st->codecpar->extradata_size = metadata_size + 8;
              AV_WL32(st->codecpar->extradata, MKTAG('f','L','a','C'));
              memcpy(st->codecpar->extradata + 4, header, 4);
              memcpy(st->codecpar->extradata + 8, buffer, metadata_size);
              av_freep(&buffer);
  
              /* get sample rate and sample count from STREAMINFO header;
               * other parameters will be extracted by the parser */
              samplerate = AV_RB24(st->codecpar->extradata + 8 + 10) >> 4;
              samples    = (AV_RB64(st->codecpar->extradata + 8 + 13) >> 24) & ((1ULL << 36) - 1);
  
              /* set time base and duration */
              if (samplerate > 0) {
                  avpriv_set_pts_info(st, 64, 1, samplerate);
                  if (samples > 0)
                      st->duration = samples;
              }
          } else if (metadata_type == FLAC_METADATA_TYPE_CUESHEET) {
              uint8_t isrc[13];
              uint64_t start;
              const uint8_t *offset;
              int i, chapters, track, ti;
              if (metadata_size < 431)
                  RETURN_ERROR(AVERROR_INVALIDDATA);
              offset = buffer + 395;
              chapters = bytestream_get_byte(&offset) - 1;
              if (chapters <= 0)
                  RETURN_ERROR(AVERROR_INVALIDDATA);
              for (i = 0; i < chapters; i++) {
                  if (offset + 36 - buffer > metadata_size)
                      RETURN_ERROR(AVERROR_INVALIDDATA);
                  start = bytestream_get_be64(&offset);
                  track = bytestream_get_byte(&offset);
                  bytestream_get_buffer(&offset, isrc, 12);
                  isrc[12] = 0;
                  offset += 14;
                  ti = bytestream_get_byte(&offset);
                  if (ti <= 0) RETURN_ERROR(AVERROR_INVALIDDATA);
                  offset += ti * 12;
                  avpriv_new_chapter(s, track, st->time_base, start, AV_NOPTS_VALUE, isrc);
              }
              av_freep(&buffer);
          } else if (metadata_type == FLAC_METADATA_TYPE_PICTURE) {
              ret = ff_flac_parse_picture(s, buffer, metadata_size);
              av_freep(&buffer);
              if (ret < 0) {
                  av_log(s, AV_LOG_ERROR, "Error parsing attached picture.\n");
                  return ret;
              }
          } else if (metadata_type == FLAC_METADATA_TYPE_SEEKTABLE) {
              const uint8_t *seekpoint = buffer;
              int i, seek_point_count = metadata_size/SEEKPOINT_SIZE;
              flac->found_seektable = 1;
              if ((s->flags&AVFMT_FLAG_FAST_SEEK)) {
                  for(i=0; i<seek_point_count; i++) {
                      int64_t timestamp = bytestream_get_be64(&seekpoint);
                      int64_t pos = bytestream_get_be64(&seekpoint);
                      /* skip number of samples */
                      bytestream_get_be16(&seekpoint);
                      av_add_index_entry(st, pos, timestamp, 0, 0, AVINDEX_KEYFRAME);
                  }
              }
              av_freep(&buffer);
          }
          else {
  
              /* STREAMINFO must be the first block */
              if (!found_streaminfo) {
                  RETURN_ERROR(AVERROR_INVALIDDATA);
              }
              /* process supported blocks other than STREAMINFO */
              if (metadata_type == FLAC_METADATA_TYPE_VORBIS_COMMENT) {
                  AVDictionaryEntry *chmask;
                  /* append VorbisComment to extradata */
                  tmp = av_realloc(st->codecpar->extradata, st->codecpar->extradata_size + 4 + metadata_size + AV_INPUT_BUFFER_PADDING_SIZE);
                  if (!tmp) {
                    RETURN_ERROR(AVERROR(ENOMEM));
                  }
                  st->codecpar->extradata = tmp;
                  tmp += st->codecpar->extradata_size;
                  memcpy(tmp, header, 4);
                  memcpy(tmp + 4, buffer, metadata_size);
                  st->codecpar->extradata_size = st->codecpar->extradata_size + 4 + metadata_size;
  
                  ret = ff_vorbis_comment(s, &s->metadata, buffer, metadata_size, 1);
                  if (ret < 0) {
                      av_log(s, AV_LOG_WARNING, "error parsing VorbisComment metadata\n");
                  } else if (ret > 0) {
                      s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
                  }
  
                  /* parse the channels mask if present */
                  chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);
                  if (chmask) {
                      uint64_t mask = strtol(chmask->value, NULL, 0);
                      if (!mask || mask & ~0x3ffffULL) {
                          av_log(s, AV_LOG_WARNING,
                                 "Invalid value of WAVEFORMATEXTENSIBLE_CHANNEL_MASK\n");
                      } else {
                          st->codecpar->channel_layout = mask;
                          av_dict_set(&s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);
                      }
                  }
              }
              av_freep(&buffer);
          }
      }
  
      ret = ff_replaygain_export(st, s->metadata);
      if (ret < 0)
          return ret;
  
      reset_index_position(avio_tell(s->pb), st);
      return 0;
  
  fail:
      av_free(buffer);
      return ret;
  }
  
  static int raw_flac_probe(const AVProbeData *p)
  {
      if ((p->buf[2] & 0xF0) == 0)    // blocksize code invalid
          return 0;
      if ((p->buf[2] & 0x0F) == 0x0F) // sample rate code invalid
          return 0;
      if ((p->buf[3] & 0xF0) >= FLAC_MAX_CHANNELS + FLAC_CHMODE_MID_SIDE << 4)
          // channel mode invalid
          return 0;
      if ((p->buf[3] & 0x06) == 0x06) // bits per sample code invalid
          return 0;
      if ((p->buf[3] & 0x01) == 0x01) // reserved bit set
          return 0;
      return AVPROBE_SCORE_EXTENSION / 4 + 1;
  }
  
  static int flac_probe(const AVProbeData *p)
  {
      if ((AV_RB16(p->buf) & 0xFFFE) == 0xFFF8)
          return raw_flac_probe(p);
  
      /* file header + metadata header + checked bytes of streaminfo */
      if (p->buf_size >= 4 + 4 + 13) {
          int type           = p->buf[4] & 0x7f;
          int size           = AV_RB24(p->buf + 5);
          int min_block_size = AV_RB16(p->buf + 8);
          int max_block_size = AV_RB16(p->buf + 10);
          int sample_rate    = AV_RB24(p->buf + 18) >> 4;
  
          if (memcmp(p->buf, "fLaC", 4))
              return 0;
          if (type == FLAC_METADATA_TYPE_STREAMINFO &&
              size == FLAC_STREAMINFO_SIZE          &&
              min_block_size >= 16                  &&
              max_block_size >= min_block_size      &&
              sample_rate && sample_rate <= 655350)
              return AVPROBE_SCORE_MAX;
          return AVPROBE_SCORE_EXTENSION;
      }
  
      return 0;
  }
  
  static av_unused int64_t flac_read_timestamp(AVFormatContext *s, int stream_index,
                                               int64_t *ppos, int64_t pos_limit)
  {
      AVPacket pkt, out_pkt;
      AVStream *st = s->streams[stream_index];
      AVCodecParserContext *parser;
      int ret;
      int64_t pts = AV_NOPTS_VALUE;
  
      if (avio_seek(s->pb, *ppos, SEEK_SET) < 0)
          return AV_NOPTS_VALUE;
  
      av_init_packet(&pkt);
      parser = av_parser_init(st->codecpar->codec_id);
      if (!parser){
          return AV_NOPTS_VALUE;
      }
      parser->flags |= PARSER_FLAG_USE_CODEC_TS;
  
      for (;;){
          ret = ff_raw_read_partial_packet(s, &pkt);
          if (ret < 0){
              if (ret == AVERROR(EAGAIN))
                  continue;
              else {
                  av_packet_unref(&pkt);
                  av_assert1(!pkt.size);
              }
          }
          av_init_packet(&out_pkt);
          av_parser_parse2(parser, st->internal->avctx,
                           &out_pkt.data, &out_pkt.size, pkt.data, pkt.size,
                           pkt.pts, pkt.dts, *ppos);
  
          av_packet_unref(&pkt);
          if (out_pkt.size){
              int size = out_pkt.size;
              if (parser->pts != AV_NOPTS_VALUE){
                  // seeking may not have started from beginning of a frame
                  // calculate frame start position from next frame backwards
                  *ppos = parser->next_frame_offset - size;
                  pts = parser->pts;
                  break;
              }
          } else if (ret < 0)
              break;
      }
      av_parser_close(parser);
      return pts;
  }
  
  static int flac_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags) {
      int index;
      int64_t pos;
      AVIndexEntry e;
      FLACDecContext *flac = s->priv_data;
  
      if (!flac->found_seektable || !(s->flags&AVFMT_FLAG_FAST_SEEK)) {
          return -1;
      }
  
      index = av_index_search_timestamp(s->streams[0], timestamp, flags);
      if(index<0 || index >= s->streams[0]->nb_index_entries)
          return -1;
  
      e = s->streams[0]->index_entries[index];
      pos = avio_seek(s->pb, e.pos, SEEK_SET);
      if (pos >= 0) {
          return 0;
      }
      return -1;
  }
  
  FF_RAW_DEMUXER_CLASS(flac)
  AVInputFormat ff_flac_demuxer = {
      .name           = "flac",
      .long_name      = NULL_IF_CONFIG_SMALL("raw FLAC"),
      .read_probe     = flac_probe,
      .read_header    = flac_read_header,
      .read_packet    = ff_raw_read_partial_packet,
      .read_seek      = flac_seek,
      .read_timestamp = flac_read_timestamp,
      .flags          = AVFMT_GENERIC_INDEX,
      .extensions     = "flac",
      .raw_codec_id   = AV_CODEC_ID_FLAC,
      .priv_data_size = sizeof(FLACDecContext),
      .priv_class     = &flac_demuxer_class,
  };
  