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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 Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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

    
24
/**
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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:
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 * 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

    
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#include "avformat.h"
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#include "avio_internal.h"
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#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"
55

    
56
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
63

    
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    uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
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    int out_bytes;                  ///< amount of outgoing bytes
66

    
67
    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)
69

    
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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
74

    
75
    int dtshd_skip;                 ///< counter used for skipping DTS-HD frames
76

    
77
    /* AVOptions: */
78
    int dtshd_rate;
79
    int dtshd_fallback;
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#define SPDIF_FLAG_BIGENDIAN    0x01
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    int spdif_flags;
82

    
83
    /// function, which generates codec dependent header information.
84
    /// Sets data_type and pkt_offset, and length_code, out_bytes, out_buf if necessary
85
    int (*header_info) (AVFormatContext *s, AVPacket *pkt);
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} IEC61937Context;
87

    
88
static const AVOption options[] = {
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{ "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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};
95

    
96
static const AVClass class = {
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    .class_name     = "spdif",
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    .item_name      = av_default_item_name,
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    .option         = options,
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    .version        = LIBAVUTIL_VERSION_INT,
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};
102

    
103
static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
104
{
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    IEC61937Context *ctx = s->priv_data;
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    int bitstream_mode = pkt->data[5] & 0x7;
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    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;
111
}
112

    
113
static int spdif_header_eac3(AVFormatContext *s, AVPacket *pkt)
114
{
115
    IEC61937Context *ctx = s->priv_data;
116
    static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
117
    int repeat = 1;
118

    
119
    if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
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        repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */
121

    
122
    ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
123
    if (!ctx->hd_buf)
124
        return AVERROR(ENOMEM);
125

    
126
    memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);
127

    
128
    ctx->hd_buf_filled += pkt->size;
129
    if (++ctx->hd_buf_count < repeat){
130
        ctx->pkt_offset = 0;
131
        return 0;
132
    }
133
    ctx->data_type   = IEC61937_EAC3;
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    ctx->pkt_offset  = 24576;
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    ctx->out_buf     = ctx->hd_buf;
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    ctx->out_bytes   = ctx->hd_buf_filled;
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    ctx->length_code = ctx->hd_buf_filled;
138

    
139
    ctx->hd_buf_count  = 0;
140
    ctx->hd_buf_filled = 0;
141
    return 0;
142
}
143

    
144
/*
145
 * DTS type IV (DTS-HD) can be transmitted with various frame repetition
146
 * periods; longer repetition periods allow for longer packets and therefore
147
 * higher bitrate. Longer repetition periods mean that the constant bitrate of
148
 * the outputted IEC 61937 stream is higher.
149
 * The repetition period is measured in IEC 60958 frames (4 bytes).
150
 */
151
static int spdif_dts4_subtype(int period)
152
{
153
    switch (period) {
154
    case 512:   return 0x0;
155
    case 1024:  return 0x1;
156
    case 2048:  return 0x2;
157
    case 4096:  return 0x3;
158
    case 8192:  return 0x4;
159
    case 16384: return 0x5;
160
    }
161
    return -1;
162
}
163

    
164
static int spdif_header_dts4(AVFormatContext *s, AVPacket *pkt, int core_size,
165
                             int sample_rate, int blocks)
166
{
167
    IEC61937Context *ctx = s->priv_data;
168
    static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
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    int pkt_size = pkt->size;
170
    int period;
171
    int subtype;
172

    
173
    if (!core_size) {
174
        av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
175
        return AVERROR(EINVAL);
176
    }
177

    
178
    if (!sample_rate) {
179
        av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
180
        return AVERROR_INVALIDDATA;
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    }
182

    
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    period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
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    subtype = spdif_dts4_subtype(period);
185

    
186
    if (subtype < 0) {
187
        av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
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               "impossible repetition period of %d for the current DTS stream"
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               " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
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               blocks << 5, sample_rate);
191
        return AVERROR(EINVAL);
192
    }
193

    
194
    /* set pkt_offset and DTS IV subtype according to the requested output
195
     * rate */
196
    ctx->pkt_offset = period * 4;
197
    ctx->data_type = IEC61937_DTSHD | subtype << 8;
198

    
199
    /* If the bitrate is too high for transmitting at the selected
200
     * repetition period setting, strip DTS-HD until a good amount
201
     * of consecutive non-overflowing HD frames have been observed.
202
     * This generally only happens if the caller is cramming a Master
203
     * Audio stream into 192kHz IEC 60958 (which may or may not fit). */
204
    if (sizeof(dtshd_start_code) + 2 + pkt_size
205
            > ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
206
        if (!ctx->dtshd_skip)
207
            av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
208
                                      "temporarily sending core only\n");
209
        if (ctx->dtshd_fallback > 0)
210
            ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
211
        else
212
            /* skip permanently (dtshd_fallback == -1) or just once
213
             * (dtshd_fallback == 0) */
214
            ctx->dtshd_skip = 1;
215
    }
216
    if (ctx->dtshd_skip && core_size) {
217
        pkt_size = core_size;
218
        if (ctx->dtshd_fallback >= 0)
219
            --ctx->dtshd_skip;
220
    }
221

    
222
    ctx->out_bytes   = sizeof(dtshd_start_code) + 2 + pkt_size;
223
    ctx->length_code = ctx->out_bytes;
224

    
225
    av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, ctx->out_bytes);
226
    if (!ctx->hd_buf)
227
        return AVERROR(ENOMEM);
228

    
229
    ctx->out_buf = ctx->hd_buf;
230

    
231
    memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
232
    AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
233
    memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);
234

    
235
    return 0;
236
}
237

    
238
static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
239
{
240
    IEC61937Context *ctx = s->priv_data;
241
    uint32_t syncword_dts = AV_RB32(pkt->data);
242
    int blocks;
243
    int sample_rate = 0;
244
    int core_size = 0;
245

    
246
    if (pkt->size < 9)
247
        return AVERROR_INVALIDDATA;
248

    
249
    switch (syncword_dts) {
250
    case DCA_MARKER_RAW_BE:
251
        blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
252
        core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
253
        sample_rate = dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
254
        break;
255
    case DCA_MARKER_RAW_LE:
256
        blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
257
        ctx->extra_bswap = 1;
258
        break;
259
    case DCA_MARKER_14B_BE:
260
        blocks =
261
            (((pkt->data[5] & 0x07) << 4) | ((pkt->data[6] & 0x3f) >> 2));
262
        break;
263
    case DCA_MARKER_14B_LE:
264
        blocks =
265
            (((pkt->data[4] & 0x07) << 4) | ((pkt->data[7] & 0x3f) >> 2));
266
        ctx->extra_bswap = 1;
267
        break;
268
    case DCA_HD_MARKER:
269
        /* We only handle HD frames that are paired with core. However,
270
           sometimes DTS-HD streams with core have a stray HD frame without
271
           core in the beginning of the stream. */
272
        av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
273
        return AVERROR_INVALIDDATA;
274
    default:
275
        av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%x\n", syncword_dts);
276
        return AVERROR_INVALIDDATA;
277
    }
278
    blocks++;
279

    
280
    if (ctx->dtshd_rate)
281
        /* DTS type IV output requested */
282
        return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);
283

    
284
    switch (blocks) {
285
    case  512 >> 5: ctx->data_type = IEC61937_DTS1; break;
286
    case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
287
    case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
288
    default:
289
        av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
290
               blocks << 5);
291
        return AVERROR(ENOSYS);
292
    }
293

    
294
    /* discard extraneous data by default */
295
    if (core_size && core_size < pkt->size) {
296
        ctx->out_bytes = core_size;
297
        ctx->length_code = core_size << 3;
298
    }
299

    
300
    ctx->pkt_offset = blocks << 7;
301

    
302
    if (ctx->out_bytes == ctx->pkt_offset) {
303
        /* The DTS stream fits exactly into the output stream, so skip the
304
         * preamble as it would not fit in there. This is the case for dts
305
         * discs and dts-in-wav. */
306
        ctx->use_preamble = 0;
307
    } else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
308
        av_log_ask_for_sample(s, "Unrecognized large DTS frame.");
309
        /* This will fail with a "bitrate too high" in the caller */
310
    }
311

    
312
    return 0;
313
}
314

    
315
static const enum IEC61937DataType mpeg_data_type[2][3] = {
316
    //     LAYER1                      LAYER2                  LAYER3
317
    { IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
318
    { IEC61937_MPEG1_LAYER1,     IEC61937_MPEG1_LAYER23,    IEC61937_MPEG1_LAYER23 },   //MPEG1
319
};
320

    
321
static int spdif_header_mpeg(AVFormatContext *s, AVPacket *pkt)
322
{
323
    IEC61937Context *ctx = s->priv_data;
324
    int version =      (pkt->data[1] >> 3) & 3;
325
    int layer   = 3 - ((pkt->data[1] >> 1) & 3);
326
    int extension = pkt->data[2] & 1;
327

    
328
    if (layer == 3 || version == 1) {
329
        av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
330
        return AVERROR_INVALIDDATA;
331
    }
332
    av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
333
    if (version == 2 && extension) {
334
        ctx->data_type  = IEC61937_MPEG2_EXT;
335
        ctx->pkt_offset = 4608;
336
    } else {
337
        ctx->data_type  = mpeg_data_type [version & 1][layer];
338
        ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
339
    }
340
    // TODO Data type dependant info (normal/karaoke, dynamic range control)
341
    return 0;
342
}
343

    
344
static int spdif_header_aac(AVFormatContext *s, AVPacket *pkt)
345
{
346
    IEC61937Context *ctx = s->priv_data;
347
    AACADTSHeaderInfo hdr;
348
    GetBitContext gbc;
349
    int ret;
350

    
351
    init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
352
    ret = ff_aac_parse_header(&gbc, &hdr);
353
    if (ret < 0) {
354
        av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
355
        return AVERROR_INVALIDDATA;
356
    }
357

    
358
    ctx->pkt_offset = hdr.samples << 2;
359
    switch (hdr.num_aac_frames) {
360
    case 1:
361
        ctx->data_type = IEC61937_MPEG2_AAC;
362
        break;
363
    case 2:
364
        ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
365
        break;
366
    case 4:
367
        ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
368
        break;
369
    default:
370
        av_log(s, AV_LOG_ERROR, "%i samples in AAC frame not supported\n",
371
               hdr.samples);
372
        return AVERROR(EINVAL);
373
    }
374
    //TODO Data type dependent info (LC profile/SBR)
375
    return 0;
376
}
377

    
378

    
379
/*
380
 * It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
381
 * they can be encapsulated in IEC 61937.
382
 * Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
383
 * to achieve constant rate.
384
 * The actual format of a MAT frame is unknown, but the below seems to work.
385
 * However, it seems it is not actually necessary for the 24 TrueHD frames to
386
 * be in an exact alignment with the MAT frame.
387
 */
388
#define MAT_FRAME_SIZE          61424
389
#define TRUEHD_FRAME_OFFSET     2560
390
#define MAT_MIDDLE_CODE_OFFSET  -4
391

    
392
static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
393
{
394
    IEC61937Context *ctx = s->priv_data;
395
    int mat_code_length = 0;
396
    const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };
397

    
398
    if (!ctx->hd_buf_count) {
399
        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 };
400
        mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
401
        memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));
402

    
403
    } else if (ctx->hd_buf_count == 12) {
404
        const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
405
        mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
406
        memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
407
               mat_middle_code, sizeof(mat_middle_code));
408
    }
409

    
410
    if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
411
        /* if such frames exist, we'd need some more complex logic to
412
         * distribute the TrueHD frames in the MAT frame */
413
        av_log(s, AV_LOG_ERROR, "TrueHD frame too big, %d bytes\n", pkt->size);
414
        av_log_ask_for_sample(s, NULL);
415
        return AVERROR_INVALIDDATA;
416
    }
417

    
418
    memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
419
           pkt->data, pkt->size);
420
    memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
421
           0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);
422

    
423
    if (++ctx->hd_buf_count < 24){
424
        ctx->pkt_offset = 0;
425
        return 0;
426
    }
427
    memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
428
    ctx->hd_buf_count = 0;
429

    
430
    ctx->data_type   = IEC61937_TRUEHD;
431
    ctx->pkt_offset  = 61440;
432
    ctx->out_buf     = ctx->hd_buf;
433
    ctx->out_bytes   = MAT_FRAME_SIZE;
434
    ctx->length_code = MAT_FRAME_SIZE;
435
    return 0;
436
}
437

    
438
static int spdif_write_header(AVFormatContext *s)
439
{
440
    IEC61937Context *ctx = s->priv_data;
441

    
442
    switch (s->streams[0]->codec->codec_id) {
443
    case CODEC_ID_AC3:
444
        ctx->header_info = spdif_header_ac3;
445
        break;
446
    case CODEC_ID_EAC3:
447
        ctx->header_info = spdif_header_eac3;
448
        break;
449
    case CODEC_ID_MP1:
450
    case CODEC_ID_MP2:
451
    case CODEC_ID_MP3:
452
        ctx->header_info = spdif_header_mpeg;
453
        break;
454
    case CODEC_ID_DTS:
455
        ctx->header_info = spdif_header_dts;
456
        break;
457
    case CODEC_ID_AAC:
458
        ctx->header_info = spdif_header_aac;
459
        break;
460
    case CODEC_ID_TRUEHD:
461
        ctx->header_info = spdif_header_truehd;
462
        ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
463
        if (!ctx->hd_buf)
464
            return AVERROR(ENOMEM);
465
        break;
466
    default:
467
        av_log(s, AV_LOG_ERROR, "codec not supported\n");
468
        return AVERROR_PATCHWELCOME;
469
    }
470
    return 0;
471
}
472

    
473
static int spdif_write_trailer(AVFormatContext *s)
474
{
475
    IEC61937Context *ctx = s->priv_data;
476
    av_freep(&ctx->buffer);
477
    av_freep(&ctx->hd_buf);
478
    return 0;
479
}
480

    
481
static av_always_inline void spdif_put_16(IEC61937Context *ctx,
482
                                          AVIOContext *pb, unsigned int val)
483
{
484
    if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
485
        avio_wb16(pb, val);
486
    else
487
        avio_wl16(pb, val);
488
}
489

    
490
static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
491
{
492
    IEC61937Context *ctx = s->priv_data;
493
    int ret, padding;
494

    
495
    ctx->out_buf = pkt->data;
496
    ctx->out_bytes = pkt->size;
497
    ctx->length_code = FFALIGN(pkt->size, 2) << 3;
498
    ctx->use_preamble = 1;
499
    ctx->extra_bswap = 0;
500

    
501
    ret = ctx->header_info(s, pkt);
502
    if (ret < 0)
503
        return ret;
504
    if (!ctx->pkt_offset)
505
        return 0;
506

    
507
    padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
508
    if (padding < 0) {
509
        av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
510
        return AVERROR(EINVAL);
511
    }
512

    
513
    if (ctx->use_preamble) {
514
        spdif_put_16(ctx, s->pb, SYNCWORD1);       //Pa
515
        spdif_put_16(ctx, s->pb, SYNCWORD2);       //Pb
516
        spdif_put_16(ctx, s->pb, ctx->data_type);  //Pc
517
        spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
518
    }
519

    
520
    if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
521
    avio_write(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
522
    } else {
523
    av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + FF_INPUT_BUFFER_PADDING_SIZE);
524
    if (!ctx->buffer)
525
        return AVERROR(ENOMEM);
526
    ff_spdif_bswap_buf16((uint16_t *)ctx->buffer, (uint16_t *)ctx->out_buf, ctx->out_bytes >> 1);
527
    avio_write(s->pb, ctx->buffer, ctx->out_bytes & ~1);
528
    }
529

    
530
    /* a final lone byte has to be MSB aligned */
531
    if (ctx->out_bytes & 1)
532
        spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);
533

    
534
    ffio_fill(s->pb, 0, padding);
535

    
536
    av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
537
           ctx->data_type, ctx->out_bytes, ctx->pkt_offset);
538

    
539
    avio_flush(s->pb);
540
    return 0;
541
}
542

    
543
AVOutputFormat ff_spdif_muxer = {
544
    "spdif",
545
    NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
546
    NULL,
547
    "spdif",
548
    sizeof(IEC61937Context),
549
    CODEC_ID_AC3,
550
    CODEC_ID_NONE,
551
    spdif_write_header,
552
    spdif_write_packet,
553
    spdif_write_trailer,
554
    .flags = AVFMT_NOTIMESTAMPS,
555
    .priv_class = &class,
556
};