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 
28 #include "avcodec.h"
29 #include "get_bits.h"
30 #include "internal.h"
31 #include "msgsmdec.h"
32 
33 #include "gsmdec_template.c"
34 
35 static av_cold int gsm_init(AVCodecContext *avctx)
36 {
37  avctx->channels = 1;
39  if (!avctx->sample_rate)
40  avctx->sample_rate = 8000;
42 
43  switch (avctx->codec_id) {
44  case AV_CODEC_ID_GSM:
45  avctx->frame_size = GSM_FRAME_SIZE;
46  avctx->block_align = GSM_BLOCK_SIZE;
47  break;
48  case AV_CODEC_ID_GSM_MS:
49  avctx->frame_size = 2 * GSM_FRAME_SIZE;
50  if (!avctx->block_align)
52  else
53  if (avctx->block_align < MSN_MIN_BLOCK_SIZE ||
54  avctx->block_align > GSM_MS_BLOCK_SIZE ||
55  (avctx->block_align - MSN_MIN_BLOCK_SIZE) % 3) {
56  av_log(avctx, AV_LOG_ERROR, "Invalid block alignment %d\n",
57  avctx->block_align);
58  return AVERROR_INVALIDDATA;
59  }
60  }
61 
62  return 0;
63 }
64 
65 static int gsm_decode_frame(AVCodecContext *avctx, void *data,
66  int *got_frame_ptr, AVPacket *avpkt)
67 {
68  AVFrame *frame = data;
69  int res;
70  GetBitContext gb;
71  const uint8_t *buf = avpkt->data;
72  int buf_size = avpkt->size;
73  int16_t *samples;
74 
75  if (buf_size < avctx->block_align) {
76  av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
77  return AVERROR_INVALIDDATA;
78  }
79 
80  /* get output buffer */
81  frame->nb_samples = avctx->frame_size;
82  if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
83  return res;
84  samples = (int16_t *)frame->data[0];
85 
86  switch (avctx->codec_id) {
87  case AV_CODEC_ID_GSM:
88  init_get_bits(&gb, buf, buf_size * 8);
89  if (get_bits(&gb, 4) != 0xd)
90  av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
91  res = gsm_decode_block(avctx, samples, &gb, GSM_13000);
92  if (res < 0)
93  return res;
94  break;
95  case AV_CODEC_ID_GSM_MS:
96  res = ff_msgsm_decode_block(avctx, samples, buf,
97  (GSM_MS_BLOCK_SIZE - avctx->block_align) / 3);
98  if (res < 0)
99  return res;
100  }
101 
102  *got_frame_ptr = 1;
103 
104  return avctx->block_align;
105 }
106 
107 static void gsm_flush(AVCodecContext *avctx)
108 {
109  GSMContext *s = avctx->priv_data;
110  memset(s, 0, sizeof(*s));
111 }
112 
113 #if CONFIG_GSM_DECODER
115  .name = "gsm",
116  .long_name = NULL_IF_CONFIG_SMALL("GSM"),
117  .type = AVMEDIA_TYPE_AUDIO,
118  .id = AV_CODEC_ID_GSM,
119  .priv_data_size = sizeof(GSMContext),
120  .init = gsm_init,
122  .flush = gsm_flush,
124 };
125 #endif
126 #if CONFIG_GSM_MS_DECODER
128  .name = "gsm_ms",
129  .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
130  .type = AVMEDIA_TYPE_AUDIO,
131  .id = AV_CODEC_ID_GSM_MS,
132  .priv_data_size = sizeof(GSMContext),
133  .init = gsm_init,
135  .flush = gsm_flush,
137 };
138 #endif
AVCodecContext::frame_size
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:1216
AVCodec
AVCodec.
Definition: codec.h:197
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
gsm_init
static av_cold int gsm_init(AVCodecContext *avctx)
Definition: gsmdec.c:35
init
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
AVCodecContext::channel_layout
uint64_t channel_layout
Audio channel layout.
Definition: avcodec.h:1247
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1196
gsmdec_template.c
AV_CH_LAYOUT_MONO
#define AV_CH_LAYOUT_MONO
Definition: channel_layout.h:90
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:324
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:369
GSM_13000
@ GSM_13000
Definition: gsm.h:33
data
const char data[16]
Definition: mxf.c:142
init_get_bits
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
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:61
GSM_FRAME_SIZE
#define GSM_FRAME_SIZE
Definition: gsm.h:30
GSM_BLOCK_SIZE
#define GSM_BLOCK_SIZE
Definition: gsmdec.c:28
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
av_cold
#define av_cold
Definition: attributes.h:90
decode
static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame, FILE *outfile)
Definition: decode_audio.c:71
ff_gsm_decoder
AVCodec ff_gsm_decoder
s
#define s(width, name)
Definition: cbs_vp9.c:257
msgsmdec.h
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
gsm_decode_frame
static int gsm_decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *avpkt)
Definition: gsmdec.c:65
get_bits.h
GSM_MS_BLOCK_SIZE
#define GSM_MS_BLOCK_SIZE
Definition: gsm.h:26
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:546
flush
static void flush(AVCodecContext *avctx)
Definition: aacdec_template.c:592
AV_CODEC_ID_GSM
@ AV_CODEC_ID_GSM
as in Berlin toast format
Definition: codec_id.h:442
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:104
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1893
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:370
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1204
MSN_MIN_BLOCK_SIZE
#define MSN_MIN_BLOCK_SIZE
Definition: gsm.h:27
AVCodecContext::channels
int channels
number of audio channels
Definition: avcodec.h:1197
gsm_decode_block
static int gsm_decode_block(AVCodecContext *avctx, int16_t *samples, GetBitContext *gb, int mode)
Definition: gsmdec_template.c:122
uint8_t
uint8_t
Definition: audio_convert.c:194
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:61
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:204
avcodec.h
AV_CODEC_ID_GSM_MS
@ AV_CODEC_ID_GSM_MS
Definition: codec_id.h:454
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:1233
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
gsm_flush
static void gsm_flush(AVCodecContext *avctx)
Definition: gsmdec.c:107
AVCodecContext
main external API structure.
Definition: avcodec.h:536
channel_layout.h
ff_gsm_ms_decoder
AVCodec ff_gsm_ms_decoder
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:563
AVPacket
This structure stores compressed data.
Definition: packet.h:346
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
GSMContext
Definition: gsmdec_data.h:28