FFmpeg
hcom.c
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1 /*
2  * HCOM audio decoder
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/intreadwrite.h"
22 #include "libavutil/mem.h"
23 
24 #include "avcodec.h"
25 #include "codec_internal.h"
26 #include "decode.h"
27 #include "get_bits.h"
28 
29 typedef struct HEntry {
30  int16_t l, r;
31 } HEntry;
32 
33 typedef struct HCOMContext {
35 
36  uint8_t first_sample;
37  uint8_t sample;
41 
43 } HCOMContext;
44 
45 static av_cold int hcom_init(AVCodecContext *avctx)
46 {
47  HCOMContext *s = avctx->priv_data;
48 
49  if (avctx->ch_layout.nb_channels != 1) {
50  av_log(avctx, AV_LOG_ERROR, "invalid number of channels\n");
51  return AVERROR_INVALIDDATA;
52  }
53 
54  if (avctx->extradata_size <= 7)
55  return AVERROR_INVALIDDATA;
56  s->dict_entries = AV_RB16(avctx->extradata);
57  if (avctx->extradata_size < s->dict_entries * 4 + 7 ||
58  s->dict_entries == 0)
59  return AVERROR_INVALIDDATA;
60  s->delta_compression = AV_RB32(avctx->extradata + 2);
61  s->sample = s->first_sample = avctx->extradata[avctx->extradata_size - 1];
62 
63  s->dict = av_calloc(s->dict_entries, sizeof(*s->dict));
64  if (!s->dict)
65  return AVERROR(ENOMEM);
66  for (int i = 0; i < s->dict_entries; i++) {
67  s->dict[i].l = AV_RB16(avctx->extradata + 6 + 4 * i);
68  s->dict[i].r = AV_RB16(avctx->extradata + 6 + 4 * i + 2);
69  if (s->dict[i].l >= 0 &&
70  (s->dict[i].l >= s->dict_entries ||
71  s->dict[i].r >= s->dict_entries ||
72  s->dict[i].r < 0 ))
73  return AVERROR_INVALIDDATA;
74  }
75  if (s->dict[0].l < 0)
76  return AVERROR_INVALIDDATA;
77 
79  s->dict_entry = 0;
80 
81  return 0;
82 }
83 
85  int *got_frame, AVPacket *pkt)
86 {
87  HCOMContext *s = avctx->priv_data;
88  GetBitContext gb;
89  int ret, n = 0;
90 
91  if (pkt->size > INT16_MAX)
92  return AVERROR_INVALIDDATA;
93 
94  frame->nb_samples = pkt->size * 8;
95  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
96  return ret;
97 
98  if ((ret = init_get_bits8(&gb, pkt->data, pkt->size)) < 0)
99  return ret;
100 
101  while (get_bits_left(&gb) > 0) {
102  if (get_bits1(&gb))
103  s->dict_entry = s->dict[s->dict_entry].r;
104  else
105  s->dict_entry = s->dict[s->dict_entry].l;
106 
107  if (s->dict[s->dict_entry].l < 0) {
108  int16_t datum;
109 
110  datum = s->dict[s->dict_entry].r;
111 
112  if (!s->delta_compression)
113  s->sample = 0;
114  s->sample = (s->sample + datum) & 0xFF;
115 
116  frame->data[0][n++] = s->sample;
117 
118  s->dict_entry = 0;
119  }
120  }
121 
122  frame->nb_samples = n;
123 
124  *got_frame = 1;
125 
126  return pkt->size;
127 }
128 
130 {
131  HCOMContext *s = avctx->priv_data;
132 
133  av_freep(&s->dict);
134 
135  return 0;
136 }
137 
139  .p.name = "hcom",
140  CODEC_LONG_NAME("HCOM Audio"),
141  .p.type = AVMEDIA_TYPE_AUDIO,
142  .p.id = AV_CODEC_ID_HCOM,
143  .priv_data_size = sizeof(HCOMContext),
144  .init = hcom_init,
145  .close = hcom_close,
147  .p.capabilities = AV_CODEC_CAP_DR1,
148  .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
149 };
FF_CODEC_CAP_INIT_CLEANUP
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: codec_internal.h:42
get_bits_left
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:695
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
AV_CODEC_ID_HCOM
@ AV_CODEC_ID_HCOM
Definition: codec_id.h:529
HCOMContext::avctx
AVCodecContext * avctx
Definition: hcom.c:34
HEntry
Definition: hcom.c:29
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:374
AVPacket::data
uint8_t * data
Definition: packet.h:524
FFCodec
Definition: codec_internal.h:127
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:313
HCOMContext
Definition: hcom.c:33
hcom_init
static av_cold int hcom_init(AVCodecContext *avctx)
Definition: hcom.c:45
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
GetBitContext
Definition: get_bits.h:108
pkt
AVPacket * pkt
Definition: movenc.c:60
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
init_get_bits8
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:545
AVCodecContext::extradata_size
int extradata_size
Definition: avcodec.h:524
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:287
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
HCOMContext::dict
HEntry * dict
Definition: hcom.c:42
decode.h
get_bits.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:388
HEntry::l
int16_t l
Definition: hcom.c:30
hcom_decode
static int hcom_decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame, AVPacket *pkt)
Definition: hcom.c:84
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1554
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:366
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
hcom_close
static av_cold int hcom_close(AVCodecContext *avctx)
Definition: hcom.c:129
AVPacket::size
int size
Definition: packet.h:525
codec_internal.h
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1057
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
HEntry::r
int16_t r
Definition: hcom.c:30
ff_hcom_decoder
const FFCodec ff_hcom_decoder
Definition: hcom.c:138
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
AVCodecContext::extradata
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
Definition: avcodec.h:523
AV_SAMPLE_FMT_U8
@ AV_SAMPLE_FMT_U8
unsigned 8 bits
Definition: samplefmt.h:57
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
av_calloc
void * av_calloc(size_t nmemb, size_t size)
Definition: mem.c:264
HCOMContext::dict_entry
int dict_entry
Definition: hcom.c:39
avcodec.h
ret
ret
Definition: filter_design.txt:187
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
HCOMContext::first_sample
uint8_t first_sample
Definition: hcom.c:36
HCOMContext::dict_entries
int dict_entries
Definition: hcom.c:38
AVCodecContext
main external API structure.
Definition: avcodec.h:445
HCOMContext::delta_compression
int delta_compression
Definition: hcom.c:40
mem.h
AVPacket
This structure stores compressed data.
Definition: packet.h:501
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:472
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
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
HCOMContext::sample
uint8_t sample
Definition: hcom.c:37
AV_RB16
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_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:98