1/*
2 * IEC 61937 muxer
3 * Copyright (c) 2009 Bartlomiej Wolowiec
4 * Copyright (c) 2010 Anssi Hannula
5 * Copyright (c) 2010 Carl Eugen Hoyos
6 *
7 * This file is part of Libav.
8 *
9 * Libav is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * Libav is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with Libav; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24/**
25 * @file
26 * IEC-61937 encapsulation of various formats, used by S/PDIF
27 * @author Bartlomiej Wolowiec
28 * @author Anssi Hannula
29 * @author Carl Eugen Hoyos
30 */
31
32/*
33 * Terminology used in specification:
34 * data-burst - IEC61937 frame, contains header and encapsuled frame
35 * burst-preambule - IEC61937 frame header, contains 16-bits words named Pa, Pb, Pc and Pd
36 * burst-payload - encapsuled frame
37 * Pa, Pb - syncword - 0xF872, 0x4E1F
38 * Pc - burst-info, contains data-type (bits 0-6), error flag (bit 7), data-type-dependent info (bits 8-12)
39 *      and bitstream number (bits 13-15)
40 * data-type - determines type of encapsuled frames
41 * Pd - length code (number of bits or bytes of encapsuled frame - according to data_type)
42 *
43 * IEC 61937 frames at normal usage start every specific count of bytes,
44 *      dependent from data-type (spaces between packets are filled by zeros)
45 */
46
47#include "avformat.h"
48#include "avio_internal.h"
49#include "spdif.h"
50#include "libavcodec/ac3.h"
51#include "libavcodec/dca.h"
52#include "libavcodec/dcadata.h"
53#include "libavcodec/aacadtsdec.h"
54#include "libavutil/opt.h"
55
56typedef struct IEC61937Context {
57    const AVClass *av_class;
58    enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
59    int length_code;                ///< length code in bits or bytes, depending on data type
60    int pkt_offset;                 ///< data burst repetition period in bytes
61    uint8_t *buffer;                ///< allocated buffer, used for swap bytes
62    int buffer_size;                ///< size of allocated buffer
63
64    uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
65    int out_bytes;                  ///< amount of outgoing bytes
66
67    int use_preamble;               ///< preamble enabled (disabled for exactly pre-padded DTS)
68    int extra_bswap;                ///< extra bswap for payload (for LE DTS => standard BE DTS)
69
70    uint8_t *hd_buf;                ///< allocated buffer to concatenate hd audio frames
71    int hd_buf_size;                ///< size of the hd audio buffer
72    int hd_buf_count;               ///< number of frames in the hd audio buffer
73    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;
80#define SPDIF_FLAG_BIGENDIAN    0x01
81    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);
86} IEC61937Context;
87
88static const AVOption options[] = {
89{ "spdif_flags", "IEC 61937 encapsulation flags", offsetof(IEC61937Context, spdif_flags), AV_OPT_TYPE_FLAGS, {.dbl = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
90{ "be", "output in big-endian format (for use as s16be)", 0, AV_OPT_TYPE_CONST, {.dbl = SPDIF_FLAG_BIGENDIAN},  0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
91{ "dtshd_rate", "mux complete DTS frames in HD mode at the specified IEC958 rate (in Hz, default 0=disabled)", offsetof(IEC61937Context, dtshd_rate), AV_OPT_TYPE_INT, {.dbl = 0}, 0, 768000, AV_OPT_FLAG_ENCODING_PARAM },
92{ "dtshd_fallback_time", "min secs to strip HD for after an overflow (-1: till the end, default 60)", offsetof(IEC61937Context, dtshd_fallback), AV_OPT_TYPE_INT, {.dbl = 60}, -1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
93{ NULL },
94};
95
96static const AVClass class = {
97    .class_name     = "spdif",
98    .item_name      = av_default_item_name,
99    .option         = options,
100    .version        = LIBAVUTIL_VERSION_INT,
101};
102
103static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
104{
105    IEC61937Context *ctx = s->priv_data;
106    int bitstream_mode = pkt->data[5] & 0x7;
107
108    ctx->data_type  = IEC61937_AC3 | (bitstream_mode << 8);
109    ctx->pkt_offset = AC3_FRAME_SIZE << 2;
110    return 0;
111}
112
113static 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 */
120        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;
134    ctx->pkt_offset  = 24576;
135    ctx->out_buf     = ctx->hd_buf;
136    ctx->out_bytes   = ctx->hd_buf_filled;
137    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 */
151static 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
164static 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 };
169    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;
181    }
182
183    period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
184    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 "
188               "impossible repetition period of %d for the current DTS stream"
189               " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
190               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
224    /* Align so that (length_code & 0xf) == 0x8. This is reportedly needed
225     * with some receivers, but the exact requirement is unconfirmed. */
226    ctx->length_code = FFALIGN(ctx->out_bytes + 0x8, 0x10) - 0x8;
227
228    av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, 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
241static 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
318static 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
324static 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
347static 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 = avpriv_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
395static 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
441static 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
476static 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
484static av_always_inline void spdif_put_16(IEC61937Context *ctx,
485                                          AVIOContext *pb, unsigned int val)
486{
487    if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
488        avio_wb16(pb, val);
489    else
490        avio_wl16(pb, val);
491}
492
493static 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    avio_write(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    avio_write(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    ffio_fill(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    avio_flush(s->pb);
543    return 0;
544}
545
546AVOutputFormat ff_spdif_muxer = {
547    .name              = "spdif",
548    .long_name         = NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
549    .extensions        = "spdif",
550    .priv_data_size    = sizeof(IEC61937Context),
551    .audio_codec       = CODEC_ID_AC3,
552    .video_codec       = CODEC_ID_NONE,
553    .write_header      = spdif_write_header,
554    .write_packet      = spdif_write_packet,
555    .write_trailer     = spdif_write_trailer,
556    .flags = AVFMT_NOTIMESTAMPS,
557    .priv_class = &class,
558};
559