FFmpeg
gsmdec.c
Go to the documentation of this file.
1 /*
2  * gsm 06.10 decoder
3  * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg 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  * FFmpeg 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 FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 /**
23  * @file
24  * GSM decoder
25  */
26 
27 #include "config_components.h"
28 
30 #include "avcodec.h"
31 #include "codec_internal.h"
32 #include "decode.h"
33 #include "get_bits.h"
34 #include "msgsmdec.h"
35 
36 #include "gsmdec_template.c"
37 
38 static av_cold int gsm_init(AVCodecContext *avctx)
39 {
42  if (!avctx->sample_rate)
43  avctx->sample_rate = 8000;
45 
46  switch (avctx->codec_id) {
47  case AV_CODEC_ID_GSM:
48  avctx->frame_size = GSM_FRAME_SIZE;
49  avctx->block_align = GSM_BLOCK_SIZE;
50  break;
51  case AV_CODEC_ID_GSM_MS:
52  avctx->frame_size = 2 * GSM_FRAME_SIZE;
53  if (!avctx->block_align)
55  else
56  if (avctx->block_align < MSN_MIN_BLOCK_SIZE ||
57  avctx->block_align > GSM_MS_BLOCK_SIZE ||
58  (avctx->block_align - MSN_MIN_BLOCK_SIZE) % 3) {
59  av_log(avctx, AV_LOG_ERROR, "Invalid block alignment %d\n",
60  avctx->block_align);
61  return AVERROR_INVALIDDATA;
62  }
63  }
64 
65  return 0;
66 }
67 
69  int *got_frame_ptr, AVPacket *avpkt)
70 {
71  int res;
72  GetBitContext gb;
73  const uint8_t *buf = avpkt->data;
74  int buf_size = avpkt->size;
75  int16_t *samples;
76 
77  if (buf_size < avctx->block_align) {
78  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
79  return AVERROR_INVALIDDATA;
80  }
81 
82  /* get output buffer */
83  frame->nb_samples = avctx->frame_size;
84  if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
85  return res;
86  samples = (int16_t *)frame->data[0];
87 
88  switch (avctx->codec_id) {
89  case AV_CODEC_ID_GSM:
90  init_get_bits(&gb, buf, buf_size * 8);
91  if (get_bits(&gb, 4) != 0xd)
92  av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
93  res = gsm_decode_block(avctx, samples, &gb, GSM_13000);
94  if (res < 0)
95  return res;
96  break;
97  case AV_CODEC_ID_GSM_MS:
98  res = ff_msgsm_decode_block(avctx, samples, buf,
99  (GSM_MS_BLOCK_SIZE - avctx->block_align) / 3);
100  if (res < 0)
101  return res;
102  }
103 
104  *got_frame_ptr = 1;
105 
106  return avctx->block_align;
107 }
108 
109 static void gsm_flush(AVCodecContext *avctx)
110 {
111  GSMContext *s = avctx->priv_data;
112  memset(s, 0, sizeof(*s));
113 }
114 
115 #if CONFIG_GSM_DECODER
116 const FFCodec ff_gsm_decoder = {
117  .p.name = "gsm",
118  CODEC_LONG_NAME("GSM"),
119  .p.type = AVMEDIA_TYPE_AUDIO,
120  .p.id = AV_CODEC_ID_GSM,
121  .priv_data_size = sizeof(GSMContext),
122  .init = gsm_init,
124  .flush = gsm_flush,
125  .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
126 };
127 #endif
128 #if CONFIG_GSM_MS_DECODER
129 const FFCodec ff_gsm_ms_decoder = {
130  .p.name = "gsm_ms",
131  CODEC_LONG_NAME("GSM Microsoft variant"),
132  .p.type = AVMEDIA_TYPE_AUDIO,
133  .p.id = AV_CODEC_ID_GSM_MS,
134  .priv_data_size = sizeof(GSMContext),
135  .init = gsm_init,
137  .flush = gsm_flush,
138  .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
139 };
140 #endif
AVCodecContext::frame_size
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:1077
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
gsm_init
static av_cold int gsm_init(AVCodecContext *avctx)
Definition: gsmdec.c:38
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1050
gsmdec_template.c
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:340
AVPacket::data
uint8_t * data
Definition: packet.h:522
GSM_13000
@ GSM_13000
Definition: gsm.h:33
FFCodec
Definition: codec_internal.h:127
init_get_bits
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:514
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:361
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:335
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:1065
ff_msgsm_decode_block
int ff_msgsm_decode_block(AVCodecContext *avctx, int16_t *samples, const uint8_t *buf, int mode)
Definition: msgsmdec.c:29
GetBitContext
Definition: get_bits.h:108
GSM_FRAME_SIZE
#define GSM_FRAME_SIZE
Definition: gsm.h:30
GSM_BLOCK_SIZE
#define GSM_BLOCK_SIZE
Definition: gsmdec.c:29
gsm_decode_frame
static int gsm_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt)
Definition: gsmdec.c:68
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
av_cold
#define av_cold
Definition: attributes.h:90
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:287
s
#define s(width, name)
Definition: cbs_vp9.c:198
msgsmdec.h
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
decode.h
get_bits.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
frame
static AVFrame * frame
Definition: demux_decode.c:54
GSM_MS_BLOCK_SIZE
#define GSM_MS_BLOCK_SIZE
Definition: gsm.h:26
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:455
AV_CODEC_ID_GSM
@ AV_CODEC_ID_GSM
as in Berlin toast format
Definition: codec_id.h:458
AV_CODEC_CAP_CHANNEL_CONF
#define AV_CODEC_CAP_CHANNEL_CONF
Codec should fill in channel configuration and samplerate instead of container.
Definition: codec.h:106
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1568
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:365
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:52
AVPacket::size
int size
Definition: packet.h:523
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:303
codec_internal.h
ff_gsm_ms_decoder
const FFCodec ff_gsm_ms_decoder
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1057
MSN_MIN_BLOCK_SIZE
#define MSN_MIN_BLOCK_SIZE
Definition: gsm.h:27
AVFrame::nb_samples
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:420
gsm_decode_block
static int gsm_decode_block(AVCodecContext *avctx, int16_t *samples, GetBitContext *gb, int mode)
Definition: gsmdec_template.c:122
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:58
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
avcodec.h
AV_CODEC_ID_GSM_MS
@ AV_CODEC_ID_GSM_MS
Definition: codec_id.h:470
AVCodecContext::block_align
int block_align
number of bytes per packet if constant and known or 0 Used by some WAV based audio codecs.
Definition: avcodec.h:1083
gsm_flush
static void gsm_flush(AVCodecContext *avctx)
Definition: gsmdec.c:109
AVCodecContext
main external API structure.
Definition: avcodec.h:445
channel_layout.h
av_channel_layout_uninit
void av_channel_layout_uninit(AVChannelLayout *channel_layout)
Free any allocated data in the channel layout and reset the channel count to 0.
Definition: channel_layout.c:432
ff_gsm_decoder
const FFCodec ff_gsm_decoder
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:378
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
AVPacket
This structure stores compressed data.
Definition: packet.h:499
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
GSMContext
Definition: gsmdec_data.h:27