diff options
Diffstat (limited to 'libavcodec/mp3_header_decompress_bsf.c')
-rw-r--r-- | libavcodec/mp3_header_decompress_bsf.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/libavcodec/mp3_header_decompress_bsf.c b/libavcodec/mp3_header_decompress_bsf.c new file mode 100644 index 0000000..22c1ef0 --- /dev/null +++ b/libavcodec/mp3_header_decompress_bsf.c @@ -0,0 +1,124 @@ +/* + * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at> + * + * 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/common.h" +#include "libavutil/intreadwrite.h" +#include "avcodec.h" +#include "bsf.h" +#include "mpegaudiodecheader.h" +#include "mpegaudiodata.h" + + +static int mp3_header_decompress(AVBSFContext *ctx, AVPacket *out) +{ + AVPacket *in; + uint32_t header; + int sample_rate= ctx->par_in->sample_rate; + int sample_rate_index=0; + int lsf, mpeg25, bitrate_index, frame_size, ret; + uint8_t *buf; + int buf_size; + + ret = ff_bsf_get_packet(ctx, &in); + if (ret < 0) + return ret; + + buf = in->data; + buf_size = in->size; + + header = AV_RB32(buf); + if(ff_mpa_check_header(header) >= 0){ + av_packet_move_ref(out, in); + av_packet_free(&in); + + return 0; + } + + if(ctx->par_in->extradata_size != 15 || strcmp(ctx->par_in->extradata, "FFCMP3 0.0")){ + av_log(ctx, AV_LOG_ERROR, "Extradata invalid %d\n", ctx->par_in->extradata_size); + ret = AVERROR(EINVAL); + goto fail; + } + + header= AV_RB32(ctx->par_in->extradata+11) & MP3_MASK; + + lsf = sample_rate < (24000+32000)/2; + mpeg25 = sample_rate < (12000+16000)/2; + sample_rate_index= (header>>10)&3; + sample_rate= avpriv_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off + + for(bitrate_index=2; bitrate_index<30; bitrate_index++){ + frame_size = avpriv_mpa_bitrate_tab[lsf][2][bitrate_index>>1]; + frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1); + if(frame_size == buf_size + 4) + break; + if(frame_size == buf_size + 6) + break; + } + if(bitrate_index == 30){ + av_log(ctx, AV_LOG_ERROR, "Could not find bitrate_index.\n"); + ret = AVERROR(EINVAL); + goto fail; + } + + header |= (bitrate_index&1)<<9; + header |= (bitrate_index>>1)<<12; + header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0 + + ret = av_new_packet(out, frame_size); + if (ret < 0) + goto fail; + ret = av_packet_copy_props(out, in); + if (ret < 0) { + av_packet_free(&out); + goto fail; + } + memcpy(out->data + frame_size - buf_size, buf, buf_size + AV_INPUT_BUFFER_PADDING_SIZE); + + if(ctx->par_in->channels==2){ + uint8_t *p= out->data + frame_size - buf_size; + if(lsf){ + FFSWAP(int, p[1], p[2]); + header |= (p[1] & 0xC0)>>2; + p[1] &= 0x3F; + }else{ + header |= p[1] & 0x30; + p[1] &= 0xCF; + } + } + + AV_WB32(out->data, header); + + ret = 0; + +fail: + av_packet_free(&in); + return ret; +} + +static const enum AVCodecID codec_ids[] = { + AV_CODEC_ID_MP3, AV_CODEC_ID_NONE, +}; + +const AVBitStreamFilter ff_mp3_header_decompress_bsf = { + .name = "mp3decomp", + .filter = mp3_header_decompress, + .codec_ids = codec_ids, +}; |