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1 /*
2  * LPCM codecs for PCM formats found in Video DVD streams
3  * Copyright (c) 2013 Christian Schmidt
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  * LPCM codecs for PCM formats found in Video DVD streams
25  */
26 
27 #include "avcodec.h"
28 #include "bytestream.h"
29 #include "codec_internal.h"
30 #include "internal.h"
31 
32 typedef struct PCMDVDContext {
33     uint32_t last_header;    // Cached header to see if parsing is needed
34     int block_size;          // Size of a block of samples in bytes
35     int last_block_size;     // Size of the last block of samples in bytes
36     int samples_per_block;   // Number of samples per channel per block
37     int groups_per_block;    // Number of 20/24-bit sample groups per block
38     int extra_sample_count;  // Number of leftover samples in the buffer
39     uint8_t extra_samples[8 * 3 * 4];  // Space for leftover samples from a frame
40                                        // (8 channels, 3B/sample, 4 samples/block)
41 } PCMDVDContext;
42 
pcm_dvd_decode_init(AVCodecContext * avctx)43 static av_cold int pcm_dvd_decode_init(AVCodecContext *avctx)
44 {
45     PCMDVDContext *s = avctx->priv_data;
46 
47     /* Invalid header to force parsing of the first header */
48     s->last_header = -1;
49 
50     return 0;
51 }
52 
pcm_dvd_parse_header(AVCodecContext * avctx,const uint8_t * header)53 static int pcm_dvd_parse_header(AVCodecContext *avctx, const uint8_t *header)
54 {
55     /* no traces of 44100 and 32000Hz in any commercial software or player */
56     static const uint32_t frequencies[4] = { 48000, 96000, 44100, 32000 };
57     PCMDVDContext *s = avctx->priv_data;
58     int header_int = (header[0] & 0xe0) | (header[1] << 8) | (header[2] << 16);
59     int channels;
60 
61     /* early exit if the header didn't change apart from the frame number */
62     if (s->last_header == header_int)
63         return 0;
64     s->last_header = -1;
65 
66     if (avctx->debug & FF_DEBUG_PICT_INFO)
67         av_log(avctx, AV_LOG_DEBUG, "pcm_dvd_parse_header: header = %02x%02x%02x\n",
68                 header[0], header[1], header[2]);
69     /*
70      * header[0] emphasis (1), muse(1), reserved(1), frame number(5)
71      * header[1] quant (2), freq(2), reserved(1), channels(3)
72      * header[2] dynamic range control (0x80 = off)
73      */
74 
75     /* Discard potentially existing leftover samples from old channel layout */
76     s->extra_sample_count = 0;
77 
78     /* get the sample depth and derive the sample format from it */
79     avctx->bits_per_coded_sample = 16 + (header[1] >> 6 & 3) * 4;
80     if (avctx->bits_per_coded_sample == 28) {
81         av_log(avctx, AV_LOG_ERROR,
82                "PCM DVD unsupported sample depth %i\n",
83                avctx->bits_per_coded_sample);
84         return AVERROR_INVALIDDATA;
85     }
86     avctx->sample_fmt = avctx->bits_per_coded_sample == 16 ? AV_SAMPLE_FMT_S16
87                                                            : AV_SAMPLE_FMT_S32;
88     avctx->bits_per_raw_sample = avctx->bits_per_coded_sample;
89 
90     /* get the sample rate */
91     avctx->sample_rate = frequencies[header[1] >> 4 & 3];
92 
93     /* get the number of channels */
94     channels = 1 + (header[1] & 7);
95 
96     av_channel_layout_uninit(&avctx->ch_layout);
97     av_channel_layout_default(&avctx->ch_layout, channels);
98     /* calculate the bitrate */
99     avctx->bit_rate = channels *
100                       avctx->sample_rate *
101                       avctx->bits_per_coded_sample;
102 
103     /* 4 samples form a group in 20/24-bit PCM on DVD Video.
104      * A block is formed by the number of groups that are
105      * needed to complete a set of samples for each channel. */
106     if (avctx->bits_per_coded_sample == 16) {
107         s->samples_per_block = 1;
108         s->block_size        = channels * 2;
109     } else {
110         switch (channels) {
111         case 1:
112         case 2:
113         case 4:
114             /* one group has all the samples needed */
115             s->block_size        = 4 * avctx->bits_per_coded_sample / 8;
116             s->samples_per_block = 4 / channels;
117             s->groups_per_block  = 1;
118             break;
119         case 8:
120             /* two groups have all the samples needed */
121             s->block_size        = 8 * avctx->bits_per_coded_sample / 8;
122             s->samples_per_block = 1;
123             s->groups_per_block  = 2;
124             break;
125         default:
126             /* need channels groups */
127             s->block_size        = 4 * channels *
128                                    avctx->bits_per_coded_sample / 8;
129             s->samples_per_block = 4;
130             s->groups_per_block  = channels;
131             break;
132         }
133     }
134 
135     if (avctx->debug & FF_DEBUG_PICT_INFO)
136         ff_dlog(avctx,
137                 "pcm_dvd_parse_header: %d channels, %d bits per sample, %d Hz, %"PRId64" bit/s\n",
138                 avctx->ch_layout.nb_channels, avctx->bits_per_coded_sample,
139                 avctx->sample_rate, avctx->bit_rate);
140 
141     s->last_header = header_int;
142 
143     return 0;
144 }
145 
pcm_dvd_decode_samples(AVCodecContext * avctx,const uint8_t * src,void * dst,int blocks)146 static void *pcm_dvd_decode_samples(AVCodecContext *avctx, const uint8_t *src,
147                                     void *dst, int blocks)
148 {
149     PCMDVDContext *s = avctx->priv_data;
150     int16_t *dst16   = dst;
151     int32_t *dst32   = dst;
152     GetByteContext gb;
153     int i;
154     uint8_t t;
155 
156     bytestream2_init(&gb, src, blocks * s->block_size);
157     switch (avctx->bits_per_coded_sample) {
158     case 16: {
159 #if HAVE_BIGENDIAN
160         bytestream2_get_buffer(&gb, dst16, blocks * s->block_size);
161         dst16 += blocks * s->block_size / 2;
162 #else
163         int samples = blocks * avctx->ch_layout.nb_channels;
164         do {
165             *dst16++ = bytestream2_get_be16u(&gb);
166         } while (--samples);
167 #endif
168         return dst16;
169     }
170     case 20:
171         if (avctx->ch_layout.nb_channels == 1) {
172             do {
173                 for (i = 2; i; i--) {
174                     dst32[0] = bytestream2_get_be16u(&gb) << 16;
175                     dst32[1] = bytestream2_get_be16u(&gb) << 16;
176                     t = bytestream2_get_byteu(&gb);
177                     *dst32++ += (t & 0xf0) << 8;
178                     *dst32++ += (t & 0x0f) << 12;
179                 }
180             } while (--blocks);
181         } else {
182         do {
183             for (i = s->groups_per_block; i; i--) {
184                 dst32[0] = bytestream2_get_be16u(&gb) << 16;
185                 dst32[1] = bytestream2_get_be16u(&gb) << 16;
186                 dst32[2] = bytestream2_get_be16u(&gb) << 16;
187                 dst32[3] = bytestream2_get_be16u(&gb) << 16;
188                 t = bytestream2_get_byteu(&gb);
189                 *dst32++ += (t & 0xf0) << 8;
190                 *dst32++ += (t & 0x0f) << 12;
191                 t = bytestream2_get_byteu(&gb);
192                 *dst32++ += (t & 0xf0) << 8;
193                 *dst32++ += (t & 0x0f) << 12;
194             }
195         } while (--blocks);
196         }
197         return dst32;
198     case 24:
199         if (avctx->ch_layout.nb_channels == 1) {
200             do {
201                 for (i = 2; i; i--) {
202                     dst32[0] = bytestream2_get_be16u(&gb) << 16;
203                     dst32[1] = bytestream2_get_be16u(&gb) << 16;
204                     *dst32++ += bytestream2_get_byteu(&gb) << 8;
205                     *dst32++ += bytestream2_get_byteu(&gb) << 8;
206                 }
207             } while (--blocks);
208         } else {
209         do {
210             for (i = s->groups_per_block; i; i--) {
211                 dst32[0] = bytestream2_get_be16u(&gb) << 16;
212                 dst32[1] = bytestream2_get_be16u(&gb) << 16;
213                 dst32[2] = bytestream2_get_be16u(&gb) << 16;
214                 dst32[3] = bytestream2_get_be16u(&gb) << 16;
215                 *dst32++ += bytestream2_get_byteu(&gb) << 8;
216                 *dst32++ += bytestream2_get_byteu(&gb) << 8;
217                 *dst32++ += bytestream2_get_byteu(&gb) << 8;
218                 *dst32++ += bytestream2_get_byteu(&gb) << 8;
219             }
220         } while (--blocks);
221         }
222         return dst32;
223     default:
224         return NULL;
225     }
226 }
227 
pcm_dvd_decode_frame(AVCodecContext * avctx,AVFrame * frame,int * got_frame_ptr,AVPacket * avpkt)228 static int pcm_dvd_decode_frame(AVCodecContext *avctx, AVFrame *frame,
229                                 int *got_frame_ptr, AVPacket *avpkt)
230 {
231     const uint8_t *src = avpkt->data;
232     int buf_size       = avpkt->size;
233     PCMDVDContext *s   = avctx->priv_data;
234     int retval;
235     int blocks;
236     void *dst;
237 
238     if (buf_size < 3) {
239         av_log(avctx, AV_LOG_ERROR, "PCM packet too small\n");
240         return AVERROR_INVALIDDATA;
241     }
242 
243     if ((retval = pcm_dvd_parse_header(avctx, src)))
244         return retval;
245     if (s->last_block_size && s->last_block_size != s->block_size) {
246         av_log(avctx, AV_LOG_WARNING, "block_size has changed %d != %d\n", s->last_block_size, s->block_size);
247         s->extra_sample_count = 0;
248     }
249     s->last_block_size = s->block_size;
250     src      += 3;
251     buf_size -= 3;
252 
253     blocks = (buf_size + s->extra_sample_count) / s->block_size;
254 
255     /* get output buffer */
256     frame->nb_samples = blocks * s->samples_per_block;
257     if ((retval = ff_get_buffer(avctx, frame, 0)) < 0)
258         return retval;
259     dst = frame->data[0];
260 
261     /* consume leftover samples from last packet */
262     if (s->extra_sample_count) {
263         int missing_samples = s->block_size - s->extra_sample_count;
264         if (buf_size >= missing_samples) {
265             memcpy(s->extra_samples + s->extra_sample_count, src,
266                    missing_samples);
267             dst = pcm_dvd_decode_samples(avctx, s->extra_samples, dst, 1);
268             src += missing_samples;
269             buf_size -= missing_samples;
270             s->extra_sample_count = 0;
271             blocks--;
272         } else {
273             /* new packet still doesn't have enough samples */
274             memcpy(s->extra_samples + s->extra_sample_count, src, buf_size);
275             s->extra_sample_count += buf_size;
276             return avpkt->size;
277         }
278     }
279 
280     /* decode remaining complete samples */
281     if (blocks) {
282         pcm_dvd_decode_samples(avctx, src, dst, blocks);
283         buf_size -= blocks * s->block_size;
284     }
285 
286     /* store leftover samples */
287     if (buf_size) {
288         src += blocks * s->block_size;
289         memcpy(s->extra_samples, src, buf_size);
290         s->extra_sample_count = buf_size;
291     }
292 
293     *got_frame_ptr = 1;
294 
295     return avpkt->size;
296 }
297 
298 const FFCodec ff_pcm_dvd_decoder = {
299     .p.name         = "pcm_dvd",
300     .p.long_name    = NULL_IF_CONFIG_SMALL("PCM signed 16|20|24-bit big-endian for DVD media"),
301     .p.type         = AVMEDIA_TYPE_AUDIO,
302     .p.id           = AV_CODEC_ID_PCM_DVD,
303     .priv_data_size = sizeof(PCMDVDContext),
304     .init           = pcm_dvd_decode_init,
305     FF_CODEC_DECODE_CB(pcm_dvd_decode_frame),
306     .p.capabilities = AV_CODEC_CAP_CHANNEL_CONF |
307                       AV_CODEC_CAP_DR1,
308     .p.sample_fmts  = (const enum AVSampleFormat[]) {
309         AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_S32, AV_SAMPLE_FMT_NONE
310     },
311     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE,
312 };
313