FFmpeg
mp3_header_decompress_bsf.c
Go to the documentation of this file.
1 /*
2  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavutil/common.h"
22 #include "libavutil/intreadwrite.h"
23 #include "bsf.h"
24 #include "bsf_internal.h"
25 #include "mpegaudiodecheader.h"
26 #include "mpegaudiodata.h"
27 
28 
30 {
31  AVPacket *in;
32  uint32_t header;
33  int sample_rate= ctx->par_in->sample_rate;
34  int sample_rate_index=0;
35  int lsf, mpeg25, bitrate_index, frame_size, ret;
36  uint8_t *buf;
37  int buf_size;
38 
39  ret = ff_bsf_get_packet(ctx, &in);
40  if (ret < 0)
41  return ret;
42 
43  buf = in->data;
44  buf_size = in->size;
45 
46  header = AV_RB32(buf);
47  if(ff_mpa_check_header(header) >= 0){
49  av_packet_free(&in);
50 
51  return 0;
52  }
53 
54  if(ctx->par_in->extradata_size != 15 || strcmp(ctx->par_in->extradata, "FFCMP3 0.0")){
55  av_log(ctx, AV_LOG_ERROR, "Extradata invalid %d\n", ctx->par_in->extradata_size);
56  ret = AVERROR(EINVAL);
57  goto fail;
58  }
59 
60  header= AV_RB32(ctx->par_in->extradata+11) & MP3_MASK;
61 
62  lsf = sample_rate < (24000+32000)/2;
63  mpeg25 = sample_rate < (12000+16000)/2;
64  sample_rate_index= (header>>10)&3;
65  if (sample_rate_index == 3) {
67  goto fail;
68  }
69 
70  sample_rate= avpriv_mpa_freq_tab[sample_rate_index] >> (lsf + mpeg25); //in case sample rate is a little off
71 
72  for(bitrate_index=2; bitrate_index<30; bitrate_index++){
73  frame_size = avpriv_mpa_bitrate_tab[lsf][2][bitrate_index>>1];
74  frame_size = (frame_size * 144000) / (sample_rate << lsf) + (bitrate_index&1);
75  if(frame_size == buf_size + 4)
76  break;
77  if(frame_size == buf_size + 6)
78  break;
79  }
80  if(bitrate_index == 30){
81  av_log(ctx, AV_LOG_ERROR, "Could not find bitrate_index.\n");
82  ret = AVERROR(EINVAL);
83  goto fail;
84  }
85 
86  header |= (bitrate_index&1)<<9;
87  header |= (bitrate_index>>1)<<12;
88  header |= (frame_size == buf_size + 4)<<16; //FIXME actually set a correct crc instead of 0
89 
91  if (ret < 0)
92  goto fail;
94  if (ret < 0) {
96  goto fail;
97  }
98  memcpy(out->data + frame_size - buf_size, buf, buf_size + AV_INPUT_BUFFER_PADDING_SIZE);
99 
100  if(ctx->par_in->channels==2){
101  uint8_t *p= out->data + frame_size - buf_size;
102  if(lsf){
103  FFSWAP(int, p[1], p[2]);
104  header |= (p[1] & 0xC0)>>2;
105  p[1] &= 0x3F;
106  }else{
107  header |= p[1] & 0x30;
108  p[1] &= 0xCF;
109  }
110  }
111 
112  AV_WB32(out->data, header);
113 
114  ret = 0;
115 
116 fail:
117  av_packet_free(&in);
118  return ret;
119 }
120 
121 static const enum AVCodecID codec_ids[] = {
123 };
124 
126  .name = "mp3decomp",
127  .filter = mp3_header_decompress,
128  .codec_ids = codec_ids,
129 };
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:403
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
bsf_internal.h
out
FILE * out
Definition: movenc.c:54
FFSWAP
#define FFSWAP(type, a, b)
Definition: common.h:108
codec_ids
static enum AVCodecID codec_ids[]
Definition: mp3_header_decompress_bsf.c:121
AVBitStreamFilter::name
const char * name
Definition: bsf.h:99
avpriv_mpa_freq_tab
const uint16_t avpriv_mpa_freq_tab[3]
Definition: mpegaudiodata.c:40
avpriv_mpa_bitrate_tab
const uint16_t avpriv_mpa_bitrate_tab[2][3][15]
Definition: mpegaudiodata.c:30
mpegaudiodecheader.h
AVPacket::data
uint8_t * data
Definition: packet.h:365
MP3_MASK
#define MP3_MASK
Definition: mpegaudiodecheader.h:32
ff_bsf_get_packet
int ff_bsf_get_packet(AVBSFContext *ctx, AVPacket **pkt)
Called by the bitstream filters to get the next packet for filtering.
Definition: bsf.c:229
mp3_header_decompress
static int mp3_header_decompress(AVBSFContext *ctx, AVPacket *out)
Definition: mp3_header_decompress_bsf.c:29
sample_rate
sample_rate
Definition: ffmpeg_filter.c:156
av_packet_free
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
Definition: avpacket.c:70
AVBSFContext
The bitstream filter state.
Definition: bsf.h:49
bsf.h
fail
#define fail()
Definition: checkasm.h:134
AV_CODEC_ID_MP3
@ AV_CODEC_ID_MP3
preferred ID for decoding MPEG audio layer 1, 2 or 3
Definition: codec_id.h:422
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
intreadwrite.h
av_new_packet
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:94
frame_size
int frame_size
Definition: mxfenc.c:2206
ctx
AVFormatContext * ctx
Definition: movenc.c:48
av_packet_move_ref
void av_packet_move_ref(AVPacket *dst, AVPacket *src)
Move every field in src to dst and reset src.
Definition: avpacket.c:459
AVCodecID
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: codec_id.h:46
AV_WB32
#define AV_WB32(p, v)
Definition: intreadwrite.h:419
ff_mpa_check_header
static int ff_mpa_check_header(uint32_t header)
Definition: mpegaudiodecheader.h:61
AVPacket::size
int size
Definition: packet.h:366
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:96
header
static const uint8_t header[24]
Definition: sdr2.c:67
av_packet_copy_props
int av_packet_copy_props(AVPacket *dst, const AVPacket *src)
Copy only "properties" fields from src to dst.
Definition: avpacket.c:374
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:47
ff_mp3_header_decompress_bsf
const AVBitStreamFilter ff_mp3_header_decompress_bsf
Definition: mp3_header_decompress_bsf.c:125
common.h
ret
ret
Definition: filter_design.txt:187
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: avcodec.h:192
AVBitStreamFilter
Definition: bsf.h:98
mpegaudiodata.h
AVPacket
This structure stores compressed data.
Definition: packet.h:342
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59