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 FFmpeg.
8 *
9 * FFmpeg 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 * FFmpeg 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 FFmpeg; 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 <inttypes.h>
48
49#include "avformat.h"
50#include "avio_internal.h"
51#include "spdif.h"
52#include "libavcodec/ac3.h"
53#include "libavcodec/dca.h"
54#include "libavcodec/aacadtsdec.h"
55#include "libavutil/opt.h"
56
57typedef struct IEC61937Context {
58    const AVClass *av_class;
59    enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
60    int length_code;                ///< length code in bits or bytes, depending on data type
61    int pkt_offset;                 ///< data burst repetition period in bytes
62    uint8_t *buffer;                ///< allocated buffer, used for swap bytes
63    int buffer_size;                ///< size of allocated buffer
64
65    uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
66    int out_bytes;                  ///< amount of outgoing bytes
67
68    int use_preamble;               ///< preamble enabled (disabled for exactly pre-padded DTS)
69    int extra_bswap;                ///< extra bswap for payload (for LE DTS => standard BE DTS)
70
71    uint8_t *hd_buf;                ///< allocated buffer to concatenate hd audio frames
72    int hd_buf_size;                ///< size of the hd audio buffer
73    int hd_buf_count;               ///< number of frames in the hd audio buffer
74    int hd_buf_filled;              ///< amount of bytes in the hd audio buffer
75
76    int dtshd_skip;                 ///< counter used for skipping DTS-HD frames
77
78    /* AVOptions: */
79    int dtshd_rate;
80    int dtshd_fallback;
81#define SPDIF_FLAG_BIGENDIAN    0x01
82    int spdif_flags;
83
84    /// function, which generates codec dependent header information.
85    /// Sets data_type and pkt_offset, and length_code, out_bytes, out_buf if necessary
86    int (*header_info) (AVFormatContext *s, AVPacket *pkt);
87} IEC61937Context;
88
89static const AVOption options[] = {
90{ "spdif_flags", "IEC 61937 encapsulation flags", offsetof(IEC61937Context, spdif_flags), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
91{ "be", "output in big-endian format (for use as s16be)", 0, AV_OPT_TYPE_CONST, {.i64 = SPDIF_FLAG_BIGENDIAN},  0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
92{ "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, {.i64 = 0}, 0, 768000, AV_OPT_FLAG_ENCODING_PARAM },
93{ "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, {.i64 = 60}, -1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
94{ NULL },
95};
96
97static const AVClass spdif_class = {
98    .class_name     = "spdif",
99    .item_name      = av_default_item_name,
100    .option         = options,
101    .version        = LIBAVUTIL_VERSION_INT,
102};
103
104static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
105{
106    IEC61937Context *ctx = s->priv_data;
107    int bitstream_mode = pkt->data[5] & 0x7;
108
109    ctx->data_type  = IEC61937_AC3 | (bitstream_mode << 8);
110    ctx->pkt_offset = AC3_FRAME_SIZE << 2;
111    return 0;
112}
113
114static int spdif_header_eac3(AVFormatContext *s, AVPacket *pkt)
115{
116    IEC61937Context *ctx = s->priv_data;
117    static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
118    int repeat = 1;
119
120    if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
121        repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */
122
123    ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
124    if (!ctx->hd_buf)
125        return AVERROR(ENOMEM);
126
127    memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);
128
129    ctx->hd_buf_filled += pkt->size;
130    if (++ctx->hd_buf_count < repeat){
131        ctx->pkt_offset = 0;
132        return 0;
133    }
134    ctx->data_type   = IEC61937_EAC3;
135    ctx->pkt_offset  = 24576;
136    ctx->out_buf     = ctx->hd_buf;
137    ctx->out_bytes   = ctx->hd_buf_filled;
138    ctx->length_code = ctx->hd_buf_filled;
139
140    ctx->hd_buf_count  = 0;
141    ctx->hd_buf_filled = 0;
142    return 0;
143}
144
145/*
146 * DTS type IV (DTS-HD) can be transmitted with various frame repetition
147 * periods; longer repetition periods allow for longer packets and therefore
148 * higher bitrate. Longer repetition periods mean that the constant bitrate of
149 * the outputted IEC 61937 stream is higher.
150 * The repetition period is measured in IEC 60958 frames (4 bytes).
151 */
152static int spdif_dts4_subtype(int period)
153{
154    switch (period) {
155    case 512:   return 0x0;
156    case 1024:  return 0x1;
157    case 2048:  return 0x2;
158    case 4096:  return 0x3;
159    case 8192:  return 0x4;
160    case 16384: return 0x5;
161    }
162    return -1;
163}
164
165static int spdif_header_dts4(AVFormatContext *s, AVPacket *pkt, int core_size,
166                             int sample_rate, int blocks)
167{
168    IEC61937Context *ctx = s->priv_data;
169    static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
170    int pkt_size = pkt->size;
171    int period;
172    int subtype;
173
174    if (!core_size) {
175        av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
176        return AVERROR(EINVAL);
177    }
178
179    if (!sample_rate) {
180        av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
181        return AVERROR_INVALIDDATA;
182    }
183
184    period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
185    subtype = spdif_dts4_subtype(period);
186
187    if (subtype < 0) {
188        av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
189               "impossible repetition period of %d for the current DTS stream"
190               " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
191               blocks << 5, sample_rate);
192        return AVERROR(EINVAL);
193    }
194
195    /* set pkt_offset and DTS IV subtype according to the requested output
196     * rate */
197    ctx->pkt_offset = period * 4;
198    ctx->data_type = IEC61937_DTSHD | subtype << 8;
199
200    /* If the bitrate is too high for transmitting at the selected
201     * repetition period setting, strip DTS-HD until a good amount
202     * of consecutive non-overflowing HD frames have been observed.
203     * This generally only happens if the caller is cramming a Master
204     * Audio stream into 192kHz IEC 60958 (which may or may not fit). */
205    if (sizeof(dtshd_start_code) + 2 + pkt_size
206            > ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
207        if (!ctx->dtshd_skip)
208            av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
209                                      "temporarily sending core only\n");
210        if (ctx->dtshd_fallback > 0)
211            ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
212        else
213            /* skip permanently (dtshd_fallback == -1) or just once
214             * (dtshd_fallback == 0) */
215            ctx->dtshd_skip = 1;
216    }
217    if (ctx->dtshd_skip && core_size) {
218        pkt_size = core_size;
219        if (ctx->dtshd_fallback >= 0)
220            --ctx->dtshd_skip;
221    }
222
223    ctx->out_bytes   = sizeof(dtshd_start_code) + 2 + pkt_size;
224
225    /* Align so that (length_code & 0xf) == 0x8. This is reportedly needed
226     * with some receivers, but the exact requirement is unconfirmed. */
227    ctx->length_code = FFALIGN(ctx->out_bytes + 0x8, 0x10) - 0x8;
228
229    av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, ctx->out_bytes);
230    if (!ctx->hd_buf)
231        return AVERROR(ENOMEM);
232
233    ctx->out_buf = ctx->hd_buf;
234
235    memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
236    AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
237    memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);
238
239    return 0;
240}
241
242static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
243{
244    IEC61937Context *ctx = s->priv_data;
245    uint32_t syncword_dts = AV_RB32(pkt->data);
246    int blocks;
247    int sample_rate = 0;
248    int core_size = 0;
249
250    if (pkt->size < 9)
251        return AVERROR_INVALIDDATA;
252
253    switch (syncword_dts) {
254    case DCA_MARKER_RAW_BE:
255        blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
256        core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
257        sample_rate = avpriv_dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
258        break;
259    case DCA_MARKER_RAW_LE:
260        blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
261        ctx->extra_bswap = 1;
262        break;
263    case DCA_MARKER_14B_BE:
264        blocks =
265            (((pkt->data[5] & 0x07) << 4) | ((pkt->data[6] & 0x3f) >> 2));
266        break;
267    case DCA_MARKER_14B_LE:
268        blocks =
269            (((pkt->data[4] & 0x07) << 4) | ((pkt->data[7] & 0x3f) >> 2));
270        ctx->extra_bswap = 1;
271        break;
272    case DCA_HD_MARKER:
273        /* We only handle HD frames that are paired with core. However,
274           sometimes DTS-HD streams with core have a stray HD frame without
275           core in the beginning of the stream. */
276        av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
277        return AVERROR_INVALIDDATA;
278    default:
279        av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%"PRIx32"\n", syncword_dts);
280        return AVERROR_INVALIDDATA;
281    }
282    blocks++;
283
284    if (ctx->dtshd_rate)
285        /* DTS type IV output requested */
286        return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);
287
288    switch (blocks) {
289    case  512 >> 5: ctx->data_type = IEC61937_DTS1; break;
290    case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
291    case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
292    default:
293        av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
294               blocks << 5);
295        return AVERROR(ENOSYS);
296    }
297
298    /* discard extraneous data by default */
299    if (core_size && core_size < pkt->size) {
300        ctx->out_bytes = core_size;
301        ctx->length_code = core_size << 3;
302    }
303
304    ctx->pkt_offset = blocks << 7;
305
306    if (ctx->out_bytes == ctx->pkt_offset) {
307        /* The DTS stream fits exactly into the output stream, so skip the
308         * preamble as it would not fit in there. This is the case for dts
309         * discs and dts-in-wav. */
310        ctx->use_preamble = 0;
311    } else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
312        avpriv_request_sample(s, "Unrecognized large DTS frame");
313        /* This will fail with a "bitrate too high" in the caller */
314    }
315
316    return 0;
317}
318
319static const enum IEC61937DataType mpeg_data_type[2][3] = {
320    //     LAYER1                      LAYER2                  LAYER3
321    { IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
322    { IEC61937_MPEG1_LAYER1,     IEC61937_MPEG1_LAYER23,    IEC61937_MPEG1_LAYER23 },   //MPEG1
323};
324
325static int spdif_header_mpeg(AVFormatContext *s, AVPacket *pkt)
326{
327    IEC61937Context *ctx = s->priv_data;
328    int version =      (pkt->data[1] >> 3) & 3;
329    int layer   = 3 - ((pkt->data[1] >> 1) & 3);
330    int extension = pkt->data[2] & 1;
331
332    if (layer == 3 || version == 1) {
333        av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
334        return AVERROR_INVALIDDATA;
335    }
336    av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
337    if (version == 2 && extension) {
338        ctx->data_type  = IEC61937_MPEG2_EXT;
339        ctx->pkt_offset = 4608;
340    } else {
341        ctx->data_type  = mpeg_data_type [version & 1][layer];
342        ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
343    }
344    // TODO Data type dependent info (normal/karaoke, dynamic range control)
345    return 0;
346}
347
348static int spdif_header_aac(AVFormatContext *s, AVPacket *pkt)
349{
350    IEC61937Context *ctx = s->priv_data;
351    AACADTSHeaderInfo hdr;
352    GetBitContext gbc;
353    int ret;
354
355    init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
356    ret = avpriv_aac_parse_header(&gbc, &hdr);
357    if (ret < 0) {
358        av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
359        return AVERROR_INVALIDDATA;
360    }
361
362    ctx->pkt_offset = hdr.samples << 2;
363    switch (hdr.num_aac_frames) {
364    case 1:
365        ctx->data_type = IEC61937_MPEG2_AAC;
366        break;
367    case 2:
368        ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
369        break;
370    case 4:
371        ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
372        break;
373    default:
374        av_log(s, AV_LOG_ERROR,
375               "%"PRIu32" samples in AAC frame not supported\n", hdr.samples);
376        return AVERROR(EINVAL);
377    }
378    //TODO Data type dependent info (LC profile/SBR)
379    return 0;
380}
381
382
383/*
384 * It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
385 * they can be encapsulated in IEC 61937.
386 * Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
387 * to achieve constant rate.
388 * The actual format of a MAT frame is unknown, but the below seems to work.
389 * However, it seems it is not actually necessary for the 24 TrueHD frames to
390 * be in an exact alignment with the MAT frame.
391 */
392#define MAT_FRAME_SIZE          61424
393#define TRUEHD_FRAME_OFFSET     2560
394#define MAT_MIDDLE_CODE_OFFSET  -4
395
396static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
397{
398    IEC61937Context *ctx = s->priv_data;
399    int mat_code_length = 0;
400    static const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };
401
402    if (!ctx->hd_buf_count) {
403        static 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 };
404        mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
405        memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));
406
407    } else if (ctx->hd_buf_count == 12) {
408        static const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
409        mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
410        memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
411               mat_middle_code, sizeof(mat_middle_code));
412    }
413
414    if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
415        /* if such frames exist, we'd need some more complex logic to
416         * distribute the TrueHD frames in the MAT frame */
417        avpriv_request_sample(s, "Too large TrueHD frame of %d bytes",
418                              pkt->size);
419        return AVERROR_PATCHWELCOME;
420    }
421
422    memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
423           pkt->data, pkt->size);
424    memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
425           0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);
426
427    if (++ctx->hd_buf_count < 24){
428        ctx->pkt_offset = 0;
429        return 0;
430    }
431    memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
432    ctx->hd_buf_count = 0;
433
434    ctx->data_type   = IEC61937_TRUEHD;
435    ctx->pkt_offset  = 61440;
436    ctx->out_buf     = ctx->hd_buf;
437    ctx->out_bytes   = MAT_FRAME_SIZE;
438    ctx->length_code = MAT_FRAME_SIZE;
439    return 0;
440}
441
442static int spdif_write_header(AVFormatContext *s)
443{
444    IEC61937Context *ctx = s->priv_data;
445
446    switch (s->streams[0]->codec->codec_id) {
447    case AV_CODEC_ID_AC3:
448        ctx->header_info = spdif_header_ac3;
449        break;
450    case AV_CODEC_ID_EAC3:
451        ctx->header_info = spdif_header_eac3;
452        break;
453    case AV_CODEC_ID_MP1:
454    case AV_CODEC_ID_MP2:
455    case AV_CODEC_ID_MP3:
456        ctx->header_info = spdif_header_mpeg;
457        break;
458    case AV_CODEC_ID_DTS:
459        ctx->header_info = spdif_header_dts;
460        break;
461    case AV_CODEC_ID_AAC:
462        ctx->header_info = spdif_header_aac;
463        break;
464    case AV_CODEC_ID_TRUEHD:
465        ctx->header_info = spdif_header_truehd;
466        ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
467        if (!ctx->hd_buf)
468            return AVERROR(ENOMEM);
469        break;
470    default:
471        av_log(s, AV_LOG_ERROR, "codec not supported\n");
472        return AVERROR_PATCHWELCOME;
473    }
474    return 0;
475}
476
477static int spdif_write_trailer(AVFormatContext *s)
478{
479    IEC61937Context *ctx = s->priv_data;
480    av_freep(&ctx->buffer);
481    av_freep(&ctx->hd_buf);
482    return 0;
483}
484
485static av_always_inline void spdif_put_16(IEC61937Context *ctx,
486                                          AVIOContext *pb, unsigned int val)
487{
488    if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
489        avio_wb16(pb, val);
490    else
491        avio_wl16(pb, val);
492}
493
494static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
495{
496    IEC61937Context *ctx = s->priv_data;
497    int ret, padding;
498
499    ctx->out_buf = pkt->data;
500    ctx->out_bytes = pkt->size;
501    ctx->length_code = FFALIGN(pkt->size, 2) << 3;
502    ctx->use_preamble = 1;
503    ctx->extra_bswap = 0;
504
505    ret = ctx->header_info(s, pkt);
506    if (ret < 0)
507        return ret;
508    if (!ctx->pkt_offset)
509        return 0;
510
511    padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
512    if (padding < 0) {
513        av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
514        return AVERROR(EINVAL);
515    }
516
517    if (ctx->use_preamble) {
518        spdif_put_16(ctx, s->pb, SYNCWORD1);       //Pa
519        spdif_put_16(ctx, s->pb, SYNCWORD2);       //Pb
520        spdif_put_16(ctx, s->pb, ctx->data_type);  //Pc
521        spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
522    }
523
524    if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
525        avio_write(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
526    } else {
527        av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + FF_INPUT_BUFFER_PADDING_SIZE);
528        if (!ctx->buffer)
529            return AVERROR(ENOMEM);
530        ff_spdif_bswap_buf16((uint16_t *)ctx->buffer, (uint16_t *)ctx->out_buf, ctx->out_bytes >> 1);
531        avio_write(s->pb, ctx->buffer, ctx->out_bytes & ~1);
532    }
533
534    /* a final lone byte has to be MSB aligned */
535    if (ctx->out_bytes & 1)
536        spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);
537
538    ffio_fill(s->pb, 0, padding);
539
540    av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
541           ctx->data_type, ctx->out_bytes, ctx->pkt_offset);
542
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       = AV_CODEC_ID_AC3,
552    .video_codec       = AV_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        = &spdif_class,
558};
559