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1
/*
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 * IEC 61937 muxer
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 * Copyright (c) 2009 Bartlomiej Wolowiec
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 * Copyright (c) 2010 Anssi Hannula
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 * Copyright (c) 2010 Carl Eugen Hoyos
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
23

    
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/**
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 * @file
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 * IEC-61937 encapsulation of various formats, used by S/PDIF
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 * @author Bartlomiej Wolowiec
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 * @author Anssi Hannula
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 * @author Carl Eugen Hoyos
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 */
31

    
32
/*
33
 * Terminology used in specification:
34
 * data-burst - IEC61937 frame, contains header and encapsuled frame
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 * burst-preambule - IEC61937 frame header, contains 16-bits words named Pa, Pb, Pc and Pd
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 * burst-payload - encapsuled frame
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 * Pa, Pb - syncword - 0xF872, 0x4E1F
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 * Pc - burst-info, contains data-type (bits 0-6), error flag (bit 7), data-type-dependent info (bits 8-12)
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 *      and bitstream number (bits 13-15)
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 * data-type - determines type of encapsuled frames
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 * Pd - length code (number of bits or bytes of encapsuled frame - according to data_type)
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 *
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 * IEC 61937 frames at normal usage start every specific count of bytes,
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 *      dependent from data-type (spaces between packets are filled by zeros)
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 */
46

    
47
#include "avformat.h"
48
#include "spdif.h"
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#include "libavcodec/ac3.h"
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#include "libavcodec/dca.h"
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#include "libavcodec/dcadata.h"
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#include "libavcodec/aacadtsdec.h"
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#include "libavutil/opt.h"
54

    
55
typedef struct IEC61937Context {
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    const AVClass *av_class;
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    enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
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    int length_code;                ///< length code in bits or bytes, depending on data type
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    int pkt_offset;                 ///< data burst repetition period in bytes
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    uint8_t *buffer;                ///< allocated buffer, used for swap bytes
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    int buffer_size;                ///< size of allocated buffer
62

    
63
    uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
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    int out_bytes;                  ///< amount of outgoing bytes
65

    
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    int use_preamble;               ///< preamble enabled (disabled for exactly pre-padded DTS)
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    int extra_bswap;                ///< extra bswap for payload (for LE DTS => standard BE DTS)
68

    
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    uint8_t *hd_buf;                ///< allocated buffer to concatenate hd audio frames
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    int hd_buf_size;                ///< size of the hd audio buffer
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    int hd_buf_count;               ///< number of frames in the hd audio buffer
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    int hd_buf_filled;              ///< amount of bytes in the hd audio buffer
73

    
74
    int dtshd_skip;                 ///< counter used for skipping DTS-HD frames
75

    
76
    /* AVOptions: */
77
    int dtshd_rate;
78
    int dtshd_fallback;
79
#define SPDIF_FLAG_BIGENDIAN    0x01
80
    int spdif_flags;
81

    
82
    /// function, which generates codec dependent header information.
83
    /// Sets data_type and pkt_offset, and length_code, out_bytes, out_buf if necessary
84
    int (*header_info) (AVFormatContext *s, AVPacket *pkt);
85
} IEC61937Context;
86

    
87
static const AVOption options[] = {
88
{ "spdif_flags", "IEC 61937 encapsulation flags", offsetof(IEC61937Context, spdif_flags), FF_OPT_TYPE_FLAGS, 0, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
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{ "be", "output in big-endian format (for use as s16be)", 0, FF_OPT_TYPE_CONST, SPDIF_FLAG_BIGENDIAN, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
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{ "dtshd_rate", "mux complete DTS frames in HD mode at the specified IEC958 rate (in Hz, default 0=disabled)", offsetof(IEC61937Context, dtshd_rate), FF_OPT_TYPE_INT, 0, 0, 768000, AV_OPT_FLAG_ENCODING_PARAM },
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{ "dtshd_fallback_time", "min secs to strip HD for after an overflow (-1: till the end, default 60)", offsetof(IEC61937Context, dtshd_fallback), FF_OPT_TYPE_INT, 60, -1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
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{ NULL },
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};
94

    
95
static const AVClass class = { "spdif", av_default_item_name, options, LIBAVUTIL_VERSION_INT };
96

    
97
static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
98
{
99
    IEC61937Context *ctx = s->priv_data;
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    int bitstream_mode = pkt->data[5] & 0x7;
101

    
102
    ctx->data_type  = IEC61937_AC3 | (bitstream_mode << 8);
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    ctx->pkt_offset = AC3_FRAME_SIZE << 2;
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    return 0;
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}
106

    
107
static int spdif_header_eac3(AVFormatContext *s, AVPacket *pkt)
108
{
109
    IEC61937Context *ctx = s->priv_data;
110
    static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
111
    int repeat = 1;
112

    
113
    if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
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        repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */
115

    
116
    ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
117
    if (!ctx->hd_buf)
118
        return AVERROR(ENOMEM);
119

    
120
    memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);
121

    
122
    ctx->hd_buf_filled += pkt->size;
123
    if (++ctx->hd_buf_count < repeat){
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        ctx->pkt_offset = 0;
125
        return 0;
126
    }
127
    ctx->data_type   = IEC61937_EAC3;
128
    ctx->pkt_offset  = 24576;
129
    ctx->out_buf     = ctx->hd_buf;
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    ctx->out_bytes   = ctx->hd_buf_filled;
131
    ctx->length_code = ctx->hd_buf_filled;
132

    
133
    ctx->hd_buf_count  = 0;
134
    ctx->hd_buf_filled = 0;
135
    return 0;
136
}
137

    
138
/*
139
 * DTS type IV (DTS-HD) can be transmitted with various frame repetition
140
 * periods; longer repetition periods allow for longer packets and therefore
141
 * higher bitrate. Longer repetition periods mean that the constant bitrate of
142
 * the outputted IEC 61937 stream is higher.
143
 * The repetition period is measured in IEC 60958 frames (4 bytes).
144
 */
145
enum {
146
    DTS4_REP_PER_512   = 0x0,
147
    DTS4_REP_PER_1024  = 0x1,
148
    DTS4_REP_PER_2048  = 0x2,
149
    DTS4_REP_PER_4096  = 0x3,
150
    DTS4_REP_PER_8192  = 0x4,
151
    DTS4_REP_PER_16384 = 0x5,
152
};
153

    
154
static int spdif_dts4_subtype(int period)
155
{
156
    switch (period) {
157
    case 512:   return DTS4_REP_PER_512;
158
    case 1024:  return DTS4_REP_PER_1024;
159
    case 2048:  return DTS4_REP_PER_2048;
160
    case 4096:  return DTS4_REP_PER_4096;
161
    case 8192:  return DTS4_REP_PER_8192;
162
    case 16384: return DTS4_REP_PER_16384;
163
    }
164
    return -1;
165
}
166

    
167
static int spdif_header_dts4(AVFormatContext *s, AVPacket *pkt, int core_size,
168
                             int sample_rate, int blocks)
169
{
170
    IEC61937Context *ctx = s->priv_data;
171
    static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
172
    int pkt_size = pkt->size;
173
    int period;
174
    int subtype;
175

    
176
    if (!core_size) {
177
        av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
178
        return AVERROR(EINVAL);
179
    }
180

    
181
    if (!sample_rate) {
182
        av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
183
        return AVERROR_INVALIDDATA;
184
    }
185

    
186
    period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
187
    subtype = spdif_dts4_subtype(period);
188

    
189
    if (subtype < 0) {
190
        av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
191
               "impossible repetition period of %d for the current DTS stream"
192
               " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
193
               blocks << 5, sample_rate);
194
        return AVERROR(EINVAL);
195
    }
196

    
197
    /* set pkt_offset and DTS IV subtype according to the requested output
198
     * rate */
199
    ctx->pkt_offset = period * 4;
200
    ctx->data_type = IEC61937_DTSHD | subtype << 8;
201

    
202
    /* If the bitrate is too high for transmitting at the selected
203
     * repetition period setting, strip DTS-HD until a good amount
204
     * of consecutive non-overflowing HD frames have been observed.
205
     * This generally only happens if the caller is cramming a Master
206
     * Audio stream into 192kHz IEC 60958 (which may or may not fit). */
207
    if (sizeof(dtshd_start_code) + 2 + pkt_size
208
            > ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
209
        if (!ctx->dtshd_skip)
210
            av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
211
                                      "temporarily sending core only\n");
212
        if (ctx->dtshd_fallback > 0)
213
            ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
214
        else
215
            /* skip permanently (-1) or just once (0) */
216
            ctx->dtshd_skip = 1;
217
    }
218
    if (ctx->dtshd_skip && core_size) {
219
        pkt_size = core_size;
220
        if (ctx->dtshd_fallback >= 0)
221
            --ctx->dtshd_skip;
222
    }
223

    
224
    ctx->out_bytes   = sizeof(dtshd_start_code) + 2 + pkt_size;
225
    ctx->length_code = ctx->out_bytes;
226

    
227
    ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size,
228
                                  ctx->out_bytes);
229
    if (!ctx->hd_buf)
230
        return AVERROR(ENOMEM);
231

    
232
    ctx->out_buf = ctx->hd_buf;
233

    
234
    memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
235
    AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
236
    memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);
237

    
238
    return 0;
239
}
240

    
241
static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
242
{
243
    IEC61937Context *ctx = s->priv_data;
244
    uint32_t syncword_dts = AV_RB32(pkt->data);
245
    int blocks;
246
    int sample_rate = 0;
247
    int core_size = 0;
248

    
249
    if (pkt->size < 9)
250
        return AVERROR_INVALIDDATA;
251

    
252
    switch (syncword_dts) {
253
    case DCA_MARKER_RAW_BE:
254
        blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
255
        core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
256
        sample_rate = dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
257
        break;
258
    case DCA_MARKER_RAW_LE:
259
        blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
260
        ctx->extra_bswap = 1;
261
        break;
262
    case DCA_MARKER_14B_BE:
263
        blocks =
264
            (((pkt->data[5] & 0x07) << 4) | ((pkt->data[6] & 0x3f) >> 2));
265
        break;
266
    case DCA_MARKER_14B_LE:
267
        blocks =
268
            (((pkt->data[4] & 0x07) << 4) | ((pkt->data[7] & 0x3f) >> 2));
269
        ctx->extra_bswap = 1;
270
        break;
271
    case DCA_HD_MARKER:
272
        /* We only handle HD frames that are paired with core. However,
273
           sometimes DTS-HD streams with core have a stray HD frame without
274
           core in the beginning of the stream. */
275
        av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
276
        return AVERROR_INVALIDDATA;
277
    default:
278
        av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%x\n", syncword_dts);
279
        return AVERROR_INVALIDDATA;
280
    }
281
    blocks++;
282

    
283
    if (ctx->dtshd_rate)
284
        /* DTS type IV output requested */
285
        return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);
286

    
287
    switch (blocks) {
288
    case  512 >> 5: ctx->data_type = IEC61937_DTS1; break;
289
    case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
290
    case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
291
    default:
292
        av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
293
               blocks << 5);
294
        return AVERROR(ENOSYS);
295
    }
296

    
297
    /* discard extraneous data by default */
298
    if (core_size && core_size < pkt->size) {
299
        ctx->out_bytes = core_size;
300
        ctx->length_code = core_size << 3;
301
    }
302

    
303
    ctx->pkt_offset = blocks << 7;
304

    
305
    if (ctx->out_bytes == ctx->pkt_offset) {
306
        /* The DTS stream fits exactly into the output stream, so skip the
307
         * preamble as it would not fit in there. This is the case for dts
308
         * discs and dts-in-wav. */
309
        ctx->use_preamble = 0;
310
    } else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
311
        av_log_ask_for_sample(s, "Unrecognized large DTS frame.");
312
        /* This will fail with a "bitrate too high" in the caller */
313
    }
314

    
315
    return 0;
316
}
317

    
318
static const enum IEC61937DataType mpeg_data_type[2][3] = {
319
    //     LAYER1                      LAYER2                  LAYER3
320
    { IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
321
    { IEC61937_MPEG1_LAYER1,     IEC61937_MPEG1_LAYER23,    IEC61937_MPEG1_LAYER23 },   //MPEG1
322
};
323

    
324
static int spdif_header_mpeg(AVFormatContext *s, AVPacket *pkt)
325
{
326
    IEC61937Context *ctx = s->priv_data;
327
    int version =      (pkt->data[1] >> 3) & 3;
328
    int layer   = 3 - ((pkt->data[1] >> 1) & 3);
329
    int extension = pkt->data[2] & 1;
330

    
331
    if (layer == 3 || version == 1) {
332
        av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
333
        return AVERROR_INVALIDDATA;
334
    }
335
    av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
336
    if (version == 2 && extension) {
337
        ctx->data_type  = IEC61937_MPEG2_EXT;
338
        ctx->pkt_offset = 4608;
339
    } else {
340
        ctx->data_type  = mpeg_data_type [version & 1][layer];
341
        ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
342
    }
343
    // TODO Data type dependant info (normal/karaoke, dynamic range control)
344
    return 0;
345
}
346

    
347
static int spdif_header_aac(AVFormatContext *s, AVPacket *pkt)
348
{
349
    IEC61937Context *ctx = s->priv_data;
350
    AACADTSHeaderInfo hdr;
351
    GetBitContext gbc;
352
    int ret;
353

    
354
    init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
355
    ret = ff_aac_parse_header(&gbc, &hdr);
356
    if (ret < 0) {
357
        av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
358
        return AVERROR_INVALIDDATA;
359
    }
360

    
361
    ctx->pkt_offset = hdr.samples << 2;
362
    switch (hdr.num_aac_frames) {
363
    case 1:
364
        ctx->data_type = IEC61937_MPEG2_AAC;
365
        break;
366
    case 2:
367
        ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
368
        break;
369
    case 4:
370
        ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
371
        break;
372
    default:
373
        av_log(s, AV_LOG_ERROR, "%i samples in AAC frame not supported\n",
374
               hdr.samples);
375
        return AVERROR(EINVAL);
376
    }
377
    //TODO Data type dependent info (LC profile/SBR)
378
    return 0;
379
}
380

    
381

    
382
/*
383
 * It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
384
 * they can be encapsulated in IEC 61937.
385
 * Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
386
 * to achieve constant rate.
387
 * The actual format of a MAT frame is unknown, but the below seems to work.
388
 * However, it seems it is not actually necessary for the 24 TrueHD frames to
389
 * be in an exact alignment with the MAT frame.
390
 */
391
#define MAT_FRAME_SIZE          61424
392
#define TRUEHD_FRAME_OFFSET     2560
393
#define MAT_MIDDLE_CODE_OFFSET  -4
394

    
395
static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
396
{
397
    IEC61937Context *ctx = s->priv_data;
398
    int mat_code_length = 0;
399
    const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };
400

    
401
    if (!ctx->hd_buf_count) {
402
        const char mat_start_code[20] = { 0x07, 0x9E, 0x00, 0x03, 0x84, 0x01, 0x01, 0x01, 0x80, 0x00, 0x56, 0xA5, 0x3B, 0xF4, 0x81, 0x83, 0x49, 0x80, 0x77, 0xE0 };
403
        mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
404
        memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));
405

    
406
    } else if (ctx->hd_buf_count == 12) {
407
        const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
408
        mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
409
        memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
410
               mat_middle_code, sizeof(mat_middle_code));
411
    }
412

    
413
    if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
414
        /* if such frames exist, we'd need some more complex logic to
415
         * distribute the TrueHD frames in the MAT frame */
416
        av_log(s, AV_LOG_ERROR, "TrueHD frame too big, %d bytes\n", pkt->size);
417
        av_log_ask_for_sample(s, NULL);
418
        return AVERROR_INVALIDDATA;
419
    }
420

    
421
    memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
422
           pkt->data, pkt->size);
423
    memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
424
           0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);
425

    
426
    if (++ctx->hd_buf_count < 24){
427
        ctx->pkt_offset = 0;
428
        return 0;
429
    }
430
    memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
431
    ctx->hd_buf_count = 0;
432

    
433
    ctx->data_type   = IEC61937_TRUEHD;
434
    ctx->pkt_offset  = 61440;
435
    ctx->out_buf     = ctx->hd_buf;
436
    ctx->out_bytes   = MAT_FRAME_SIZE;
437
    ctx->length_code = MAT_FRAME_SIZE;
438
    return 0;
439
}
440

    
441
static int spdif_write_header(AVFormatContext *s)
442
{
443
    IEC61937Context *ctx = s->priv_data;
444

    
445
    switch (s->streams[0]->codec->codec_id) {
446
    case CODEC_ID_AC3:
447
        ctx->header_info = spdif_header_ac3;
448
        break;
449
    case CODEC_ID_EAC3:
450
        ctx->header_info = spdif_header_eac3;
451
        break;
452
    case CODEC_ID_MP1:
453
    case CODEC_ID_MP2:
454
    case CODEC_ID_MP3:
455
        ctx->header_info = spdif_header_mpeg;
456
        break;
457
    case CODEC_ID_DTS:
458
        ctx->header_info = spdif_header_dts;
459
        break;
460
    case CODEC_ID_AAC:
461
        ctx->header_info = spdif_header_aac;
462
        break;
463
    case CODEC_ID_TRUEHD:
464
        ctx->header_info = spdif_header_truehd;
465
        ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
466
        if (!ctx->hd_buf)
467
            return AVERROR(ENOMEM);
468
        break;
469
    default:
470
        av_log(s, AV_LOG_ERROR, "codec not supported\n");
471
        return AVERROR_PATCHWELCOME;
472
    }
473
    return 0;
474
}
475

    
476
static int spdif_write_trailer(AVFormatContext *s)
477
{
478
    IEC61937Context *ctx = s->priv_data;
479
    av_freep(&ctx->buffer);
480
    av_freep(&ctx->hd_buf);
481
    return 0;
482
}
483

    
484
static av_always_inline void spdif_put_16(IEC61937Context *ctx,
485
                                          ByteIOContext *pb, unsigned int val)
486
{
487
    if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
488
        put_be16(pb, val);
489
    else
490
        put_le16(pb, val);
491
}
492

    
493
static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
494
{
495
    IEC61937Context *ctx = s->priv_data;
496
    int ret, padding;
497

    
498
    ctx->out_buf = pkt->data;
499
    ctx->out_bytes = pkt->size;
500
    ctx->length_code = FFALIGN(pkt->size, 2) << 3;
501
    ctx->use_preamble = 1;
502
    ctx->extra_bswap = 0;
503

    
504
    ret = ctx->header_info(s, pkt);
505
    if (ret < 0)
506
        return ret;
507
    if (!ctx->pkt_offset)
508
        return 0;
509

    
510
    padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
511
    if (padding < 0) {
512
        av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
513
        return AVERROR(EINVAL);
514
    }
515

    
516
    if (ctx->use_preamble) {
517
        spdif_put_16(ctx, s->pb, SYNCWORD1);       //Pa
518
        spdif_put_16(ctx, s->pb, SYNCWORD2);       //Pb
519
        spdif_put_16(ctx, s->pb, ctx->data_type);  //Pc
520
        spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
521
    }
522

    
523
    if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
524
    put_buffer(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
525
    } else {
526
    av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + FF_INPUT_BUFFER_PADDING_SIZE);
527
    if (!ctx->buffer)
528
        return AVERROR(ENOMEM);
529
    ff_spdif_bswap_buf16((uint16_t *)ctx->buffer, (uint16_t *)ctx->out_buf, ctx->out_bytes >> 1);
530
    put_buffer(s->pb, ctx->buffer, ctx->out_bytes & ~1);
531
    }
532

    
533
    /* a final lone byte has to be MSB aligned */
534
    if (ctx->out_bytes & 1)
535
        spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);
536

    
537
    put_nbyte(s->pb, 0, padding);
538

    
539
    av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
540
           ctx->data_type, ctx->out_bytes, ctx->pkt_offset);
541

    
542
    put_flush_packet(s->pb);
543
    return 0;
544
}
545

    
546
AVOutputFormat ff_spdif_muxer = {
547
    "spdif",
548
    NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
549
    NULL,
550
    "spdif",
551
    sizeof(IEC61937Context),
552
    CODEC_ID_AC3,
553
    CODEC_ID_NONE,
554
    spdif_write_header,
555
    spdif_write_packet,
556
    spdif_write_trailer,
557
    .priv_class = &class,
558
};