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  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 "avformat.h"
  48. #include "avio_internal.h"
  49. #include "spdif.h"
  50. #include "libavcodec/ac3.h"
  51. #include "libavcodec/dca.h"
  52. #include "libavcodec/aacadtsdec.h"
  53. #include "libavutil/opt.h"
  54.  
  55. typedef struct IEC61937Context {
  56.     const AVClass *av_class;
  57.     enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
  58.     int length_code;                ///< length code in bits or bytes, depending on data type
  59.     int pkt_offset;                 ///< data burst repetition period in bytes
  60.     uint8_t *buffer;                ///< allocated buffer, used for swap bytes
  61.     int buffer_size;                ///< size of allocated buffer
  62.  
  63.     uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
  64.     int out_bytes;                  ///< amount of outgoing bytes
  65.  
  66.     int use_preamble;               ///< preamble enabled (disabled for exactly pre-padded DTS)
  67.     int extra_bswap;                ///< extra bswap for payload (for LE DTS => standard BE DTS)
  68.  
  69.     uint8_t *hd_buf;                ///< allocated buffer to concatenate hd audio frames
  70.     int hd_buf_size;                ///< size of the hd audio buffer
  71.     int hd_buf_count;               ///< number of frames in the hd audio buffer
  72.     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), AV_OPT_TYPE_FLAGS, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "spdif_flags" },
  89. { "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" },
  90. { "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 },
  91. { "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 },
  92. { NULL },
  93. };
  94.  
  95. static const AVClass spdif_class = {
  96.     .class_name     = "spdif",
  97.     .item_name      = av_default_item_name,
  98.     .option         = options,
  99.     .version        = LIBAVUTIL_VERSION_INT,
  100. };
  101.  
  102. static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
  103. {
  104.     IEC61937Context *ctx = s->priv_data;
  105.     int bitstream_mode = pkt->data[5] & 0x7;
  106.  
  107.     ctx->data_type  = IEC61937_AC3 | (bitstream_mode << 8);
  108.     ctx->pkt_offset = AC3_FRAME_SIZE << 2;
  109.     return 0;
  110. }
  111.  
  112. static int spdif_header_eac3(AVFormatContext *s, AVPacket *pkt)
  113. {
  114.     IEC61937Context *ctx = s->priv_data;
  115.     static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
  116.     int repeat = 1;
  117.  
  118.     if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
  119.         repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */
  120.  
  121.     ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
  122.     if (!ctx->hd_buf)
  123.         return AVERROR(ENOMEM);
  124.  
  125.     memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);
  126.  
  127.     ctx->hd_buf_filled += pkt->size;
  128.     if (++ctx->hd_buf_count < repeat){
  129.         ctx->pkt_offset = 0;
  130.         return 0;
  131.     }
  132.     ctx->data_type   = IEC61937_EAC3;
  133.     ctx->pkt_offset  = 24576;
  134.     ctx->out_buf     = ctx->hd_buf;
  135.     ctx->out_bytes   = ctx->hd_buf_filled;
  136.     ctx->length_code = ctx->hd_buf_filled;
  137.  
  138.     ctx->hd_buf_count  = 0;
  139.     ctx->hd_buf_filled = 0;
  140.     return 0;
  141. }
  142.  
  143. /*
  144.  * DTS type IV (DTS-HD) can be transmitted with various frame repetition
  145.  * periods; longer repetition periods allow for longer packets and therefore
  146.  * higher bitrate. Longer repetition periods mean that the constant bitrate of
  147.  * the outputted IEC 61937 stream is higher.
  148.  * The repetition period is measured in IEC 60958 frames (4 bytes).
  149.  */
  150. static int spdif_dts4_subtype(int period)
  151. {
  152.     switch (period) {
  153.     case 512:   return 0x0;
  154.     case 1024:  return 0x1;
  155.     case 2048:  return 0x2;
  156.     case 4096:  return 0x3;
  157.     case 8192:  return 0x4;
  158.     case 16384: return 0x5;
  159.     }
  160.     return -1;
  161. }
  162.  
  163. static int spdif_header_dts4(AVFormatContext *s, AVPacket *pkt, int core_size,
  164.                              int sample_rate, int blocks)
  165. {
  166.     IEC61937Context *ctx = s->priv_data;
  167.     static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
  168.     int pkt_size = pkt->size;
  169.     int period;
  170.     int subtype;
  171.  
  172.     if (!core_size) {
  173.         av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
  174.         return AVERROR(EINVAL);
  175.     }
  176.  
  177.     if (!sample_rate) {
  178.         av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
  179.         return AVERROR_INVALIDDATA;
  180.     }
  181.  
  182.     period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
  183.     subtype = spdif_dts4_subtype(period);
  184.  
  185.     if (subtype < 0) {
  186.         av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
  187.                "impossible repetition period of %d for the current DTS stream"
  188.                " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
  189.                blocks << 5, sample_rate);
  190.         return AVERROR(EINVAL);
  191.     }
  192.  
  193.     /* set pkt_offset and DTS IV subtype according to the requested output
  194.      * rate */
  195.     ctx->pkt_offset = period * 4;
  196.     ctx->data_type = IEC61937_DTSHD | subtype << 8;
  197.  
  198.     /* If the bitrate is too high for transmitting at the selected
  199.      * repetition period setting, strip DTS-HD until a good amount
  200.      * of consecutive non-overflowing HD frames have been observed.
  201.      * This generally only happens if the caller is cramming a Master
  202.      * Audio stream into 192kHz IEC 60958 (which may or may not fit). */
  203.     if (sizeof(dtshd_start_code) + 2 + pkt_size
  204.             > ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
  205.         if (!ctx->dtshd_skip)
  206.             av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
  207.                                       "temporarily sending core only\n");
  208.         if (ctx->dtshd_fallback > 0)
  209.             ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
  210.         else
  211.             /* skip permanently (dtshd_fallback == -1) or just once
  212.              * (dtshd_fallback == 0) */
  213.             ctx->dtshd_skip = 1;
  214.     }
  215.     if (ctx->dtshd_skip && core_size) {
  216.         pkt_size = core_size;
  217.         if (ctx->dtshd_fallback >= 0)
  218.             --ctx->dtshd_skip;
  219.     }
  220.  
  221.     ctx->out_bytes   = sizeof(dtshd_start_code) + 2 + pkt_size;
  222.  
  223.     /* Align so that (length_code & 0xf) == 0x8. This is reportedly needed
  224.      * with some receivers, but the exact requirement is unconfirmed. */
  225.     ctx->length_code = FFALIGN(ctx->out_bytes + 0x8, 0x10) - 0x8;
  226.  
  227.     av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, ctx->out_bytes);
  228.     if (!ctx->hd_buf)
  229.         return AVERROR(ENOMEM);
  230.  
  231.     ctx->out_buf = ctx->hd_buf;
  232.  
  233.     memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
  234.     AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
  235.     memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);
  236.  
  237.     return 0;
  238. }
  239.  
  240. static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
  241. {
  242.     IEC61937Context *ctx = s->priv_data;
  243.     uint32_t syncword_dts = AV_RB32(pkt->data);
  244.     int blocks;
  245.     int sample_rate = 0;
  246.     int core_size = 0;
  247.  
  248.     if (pkt->size < 9)
  249.         return AVERROR_INVALIDDATA;
  250.  
  251.     switch (syncword_dts) {
  252.     case DCA_MARKER_RAW_BE:
  253.         blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
  254.         core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
  255.         sample_rate = avpriv_dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
  256.         break;
  257.     case DCA_MARKER_RAW_LE:
  258.         blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
  259.         ctx->extra_bswap = 1;
  260.         break;
  261.     case DCA_MARKER_14B_BE:
  262.         blocks =
  263.             (((pkt->data[5] & 0x07) << 4) | ((pkt->data[6] & 0x3f) >> 2));
  264.         break;
  265.     case DCA_MARKER_14B_LE:
  266.         blocks =
  267.             (((pkt->data[4] & 0x07) << 4) | ((pkt->data[7] & 0x3f) >> 2));
  268.         ctx->extra_bswap = 1;
  269.         break;
  270.     case DCA_HD_MARKER:
  271.         /* We only handle HD frames that are paired with core. However,
  272.            sometimes DTS-HD streams with core have a stray HD frame without
  273.            core in the beginning of the stream. */
  274.         av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
  275.         return AVERROR_INVALIDDATA;
  276.     default:
  277.         av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%x\n", syncword_dts);
  278.         return AVERROR_INVALIDDATA;
  279.     }
  280.     blocks++;
  281.  
  282.     if (ctx->dtshd_rate)
  283.         /* DTS type IV output requested */
  284.         return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);
  285.  
  286.     switch (blocks) {
  287.     case  512 >> 5: ctx->data_type = IEC61937_DTS1; break;
  288.     case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
  289.     case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
  290.     default:
  291.         av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
  292.                blocks << 5);
  293.         return AVERROR(ENOSYS);
  294.     }
  295.  
  296.     /* discard extraneous data by default */
  297.     if (core_size && core_size < pkt->size) {
  298.         ctx->out_bytes = core_size;
  299.         ctx->length_code = core_size << 3;
  300.     }
  301.  
  302.     ctx->pkt_offset = blocks << 7;
  303.  
  304.     if (ctx->out_bytes == ctx->pkt_offset) {
  305.         /* The DTS stream fits exactly into the output stream, so skip the
  306.          * preamble as it would not fit in there. This is the case for dts
  307.          * discs and dts-in-wav. */
  308.         ctx->use_preamble = 0;
  309.     } else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
  310.         avpriv_request_sample(s, "Unrecognized large DTS frame");
  311.         /* This will fail with a "bitrate too high" in the caller */
  312.     }
  313.  
  314.     return 0;
  315. }
  316.  
  317. static const enum IEC61937DataType mpeg_data_type[2][3] = {
  318.     //     LAYER1                      LAYER2                  LAYER3
  319.     { IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
  320.     { IEC61937_MPEG1_LAYER1,     IEC61937_MPEG1_LAYER23,    IEC61937_MPEG1_LAYER23 },   //MPEG1
  321. };
  322.  
  323. static int spdif_header_mpeg(AVFormatContext *s, AVPacket *pkt)
  324. {
  325.     IEC61937Context *ctx = s->priv_data;
  326.     int version =      (pkt->data[1] >> 3) & 3;
  327.     int layer   = 3 - ((pkt->data[1] >> 1) & 3);
  328.     int extension = pkt->data[2] & 1;
  329.  
  330.     if (layer == 3 || version == 1) {
  331.         av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
  332.         return AVERROR_INVALIDDATA;
  333.     }
  334.     av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
  335.     if (version == 2 && extension) {
  336.         ctx->data_type  = IEC61937_MPEG2_EXT;
  337.         ctx->pkt_offset = 4608;
  338.     } else {
  339.         ctx->data_type  = mpeg_data_type [version & 1][layer];
  340.         ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
  341.     }
  342.     // TODO Data type dependent info (normal/karaoke, dynamic range control)
  343.     return 0;
  344. }
  345.  
  346. static int spdif_header_aac(AVFormatContext *s, AVPacket *pkt)
  347. {
  348.     IEC61937Context *ctx = s->priv_data;
  349.     AACADTSHeaderInfo hdr;
  350.     GetBitContext gbc;
  351.     int ret;
  352.  
  353.     init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
  354.     ret = avpriv_aac_parse_header(&gbc, &hdr);
  355.     if (ret < 0) {
  356.         av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
  357.         return AVERROR_INVALIDDATA;
  358.     }
  359.  
  360.     ctx->pkt_offset = hdr.samples << 2;
  361.     switch (hdr.num_aac_frames) {
  362.     case 1:
  363.         ctx->data_type = IEC61937_MPEG2_AAC;
  364.         break;
  365.     case 2:
  366.         ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
  367.         break;
  368.     case 4:
  369.         ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
  370.         break;
  371.     default:
  372.         av_log(s, AV_LOG_ERROR, "%i samples in AAC frame not supported\n",
  373.                hdr.samples);
  374.         return AVERROR(EINVAL);
  375.     }
  376.     //TODO Data type dependent info (LC profile/SBR)
  377.     return 0;
  378. }
  379.  
  380.  
  381. /*
  382.  * It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
  383.  * they can be encapsulated in IEC 61937.
  384.  * Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
  385.  * to achieve constant rate.
  386.  * The actual format of a MAT frame is unknown, but the below seems to work.
  387.  * However, it seems it is not actually necessary for the 24 TrueHD frames to
  388.  * be in an exact alignment with the MAT frame.
  389.  */
  390. #define MAT_FRAME_SIZE          61424
  391. #define TRUEHD_FRAME_OFFSET     2560
  392. #define MAT_MIDDLE_CODE_OFFSET  -4
  393.  
  394. static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
  395. {
  396.     IEC61937Context *ctx = s->priv_data;
  397.     int mat_code_length = 0;
  398.     static const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };
  399.  
  400.     if (!ctx->hd_buf_count) {
  401.         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 };
  402.         mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
  403.         memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));
  404.  
  405.     } else if (ctx->hd_buf_count == 12) {
  406.         static const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
  407.         mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
  408.         memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
  409.                mat_middle_code, sizeof(mat_middle_code));
  410.     }
  411.  
  412.     if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
  413.         /* if such frames exist, we'd need some more complex logic to
  414.          * distribute the TrueHD frames in the MAT frame */
  415.         avpriv_request_sample(s, "Too large TrueHD frame of %d bytes",
  416.                               pkt->size);
  417.         return AVERROR_PATCHWELCOME;
  418.     }
  419.  
  420.     memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
  421.            pkt->data, pkt->size);
  422.     memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
  423.            0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);
  424.  
  425.     if (++ctx->hd_buf_count < 24){
  426.         ctx->pkt_offset = 0;
  427.         return 0;
  428.     }
  429.     memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
  430.     ctx->hd_buf_count = 0;
  431.  
  432.     ctx->data_type   = IEC61937_TRUEHD;
  433.     ctx->pkt_offset  = 61440;
  434.     ctx->out_buf     = ctx->hd_buf;
  435.     ctx->out_bytes   = MAT_FRAME_SIZE;
  436.     ctx->length_code = MAT_FRAME_SIZE;
  437.     return 0;
  438. }
  439.  
  440. static int spdif_write_header(AVFormatContext *s)
  441. {
  442.     IEC61937Context *ctx = s->priv_data;
  443.  
  444.     switch (s->streams[0]->codec->codec_id) {
  445.     case AV_CODEC_ID_AC3:
  446.         ctx->header_info = spdif_header_ac3;
  447.         break;
  448.     case AV_CODEC_ID_EAC3:
  449.         ctx->header_info = spdif_header_eac3;
  450.         break;
  451.     case AV_CODEC_ID_MP1:
  452.     case AV_CODEC_ID_MP2:
  453.     case AV_CODEC_ID_MP3:
  454.         ctx->header_info = spdif_header_mpeg;
  455.         break;
  456.     case AV_CODEC_ID_DTS:
  457.         ctx->header_info = spdif_header_dts;
  458.         break;
  459.     case AV_CODEC_ID_AAC:
  460.         ctx->header_info = spdif_header_aac;
  461.         break;
  462.     case AV_CODEC_ID_TRUEHD:
  463.         ctx->header_info = spdif_header_truehd;
  464.         ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
  465.         if (!ctx->hd_buf)
  466.             return AVERROR(ENOMEM);
  467.         break;
  468.     default:
  469.         av_log(s, AV_LOG_ERROR, "codec not supported\n");
  470.         return AVERROR_PATCHWELCOME;
  471.     }
  472.     return 0;
  473. }
  474.  
  475. static int spdif_write_trailer(AVFormatContext *s)
  476. {
  477.     IEC61937Context *ctx = s->priv_data;
  478.     av_freep(&ctx->buffer);
  479.     av_freep(&ctx->hd_buf);
  480.     return 0;
  481. }
  482.  
  483. static av_always_inline void spdif_put_16(IEC61937Context *ctx,
  484.                                           AVIOContext *pb, unsigned int val)
  485. {
  486.     if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
  487.         avio_wb16(pb, val);
  488.     else
  489.         avio_wl16(pb, val);
  490. }
  491.  
  492. static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
  493. {
  494.     IEC61937Context *ctx = s->priv_data;
  495.     int ret, padding;
  496.  
  497.     ctx->out_buf = pkt->data;
  498.     ctx->out_bytes = pkt->size;
  499.     ctx->length_code = FFALIGN(pkt->size, 2) << 3;
  500.     ctx->use_preamble = 1;
  501.     ctx->extra_bswap = 0;
  502.  
  503.     ret = ctx->header_info(s, pkt);
  504.     if (ret < 0)
  505.         return ret;
  506.     if (!ctx->pkt_offset)
  507.         return 0;
  508.  
  509.     padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
  510.     if (padding < 0) {
  511.         av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
  512.         return AVERROR(EINVAL);
  513.     }
  514.  
  515.     if (ctx->use_preamble) {
  516.         spdif_put_16(ctx, s->pb, SYNCWORD1);       //Pa
  517.         spdif_put_16(ctx, s->pb, SYNCWORD2);       //Pb
  518.         spdif_put_16(ctx, s->pb, ctx->data_type);  //Pc
  519.         spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
  520.     }
  521.  
  522.     if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
  523.         avio_write(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
  524.     } else {
  525.         av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + FF_INPUT_BUFFER_PADDING_SIZE);
  526.         if (!ctx->buffer)
  527.             return AVERROR(ENOMEM);
  528.         ff_spdif_bswap_buf16((uint16_t *)ctx->buffer, (uint16_t *)ctx->out_buf, ctx->out_bytes >> 1);
  529.         avio_write(s->pb, ctx->buffer, ctx->out_bytes & ~1);
  530.     }
  531.  
  532.     /* a final lone byte has to be MSB aligned */
  533.     if (ctx->out_bytes & 1)
  534.         spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);
  535.  
  536.     ffio_fill(s->pb, 0, padding);
  537.  
  538.     av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
  539.            ctx->data_type, ctx->out_bytes, ctx->pkt_offset);
  540.  
  541.     return 0;
  542. }
  543.  
  544. AVOutputFormat ff_spdif_muxer = {
  545.     .name              = "spdif",
  546.     .long_name         = NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
  547.     .extensions        = "spdif",
  548.     .priv_data_size    = sizeof(IEC61937Context),
  549.     .audio_codec       = AV_CODEC_ID_AC3,
  550.     .video_codec       = AV_CODEC_ID_NONE,
  551.     .write_header      = spdif_write_header,
  552.     .write_packet      = spdif_write_packet,
  553.     .write_trailer     = spdif_write_trailer,
  554.     .flags             = AVFMT_NOTIMESTAMPS,
  555.     .priv_class        = &spdif_class,
  556. };
  557.