making act segmenter

1 files changed, 557 insertions, 0 deletions

diff --git a/ffmpeg/libavformat/spdifenc.c b/ffmpeg/libavformat/spdifenc.c
new file mode 100644
index 0000000..778ab88
--- /dev/null
+++ b/ffmpeg/libavformat/spdifenc.c
@@ -0,0 +1,557 @@
+/*
+ * IEC 61937 muxer
+ * Copyright (c) 2009 Bartlomiej Wolowiec
+ * Copyright (c) 2010 Anssi Hannula
+ * Copyright (c) 2010 Carl Eugen Hoyos
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * IEC-61937 encapsulation of various formats, used by S/PDIF
+ * @author Bartlomiej Wolowiec
+ * @author Anssi Hannula
+ * @author Carl Eugen Hoyos
+ */
+
+/*
+ * Terminology used in specification:
+ * data-burst - IEC61937 frame, contains header and encapsuled frame
+ * burst-preambule - IEC61937 frame header, contains 16-bits words named Pa, Pb, Pc and Pd
+ * burst-payload - encapsuled frame
+ * Pa, Pb - syncword - 0xF872, 0x4E1F
+ * Pc - burst-info, contains data-type (bits 0-6), error flag (bit 7), data-type-dependent info (bits 8-12)
+ *      and bitstream number (bits 13-15)
+ * data-type - determines type of encapsuled frames
+ * Pd - length code (number of bits or bytes of encapsuled frame - according to data_type)
+ *
+ * IEC 61937 frames at normal usage start every specific count of bytes,
+ *      dependent from data-type (spaces between packets are filled by zeros)
+ */
+
+#include "avformat.h"
+#include "avio_internal.h"
+#include "spdif.h"
+#include "libavcodec/ac3.h"
+#include "libavcodec/dca.h"
+#include "libavcodec/aacadtsdec.h"
+#include "libavutil/opt.h"
+
+typedef struct IEC61937Context {
+    const AVClass *av_class;
+    enum IEC61937DataType data_type;///< burst info - reference to type of payload of the data-burst
+    int length_code;                ///< length code in bits or bytes, depending on data type
+    int pkt_offset;                 ///< data burst repetition period in bytes
+    uint8_t *buffer;                ///< allocated buffer, used for swap bytes
+    int buffer_size;                ///< size of allocated buffer
+
+    uint8_t *out_buf;               ///< pointer to the outgoing data before byte-swapping
+    int out_bytes;                  ///< amount of outgoing bytes
+
+    int use_preamble;               ///< preamble enabled (disabled for exactly pre-padded DTS)
+    int extra_bswap;                ///< extra bswap for payload (for LE DTS => standard BE DTS)
+
+    uint8_t *hd_buf;                ///< allocated buffer to concatenate hd audio frames
+    int hd_buf_size;                ///< size of the hd audio buffer
+    int hd_buf_count;               ///< number of frames in the hd audio buffer
+    int hd_buf_filled;              ///< amount of bytes in the hd audio buffer
+
+    int dtshd_skip;                 ///< counter used for skipping DTS-HD frames
+
+    /* AVOptions: */
+    int dtshd_rate;
+    int dtshd_fallback;
+#define SPDIF_FLAG_BIGENDIAN    0x01
+    int spdif_flags;
+
+    /// function, which generates codec dependent header information.
+    /// Sets data_type and pkt_offset, and length_code, out_bytes, out_buf if necessary
+    int (*header_info) (AVFormatContext *s, AVPacket *pkt);
+} IEC61937Context;
+
+static const AVOption options[] = {
+{ "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" },
+{ "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" },
+{ "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 },
+{ "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 },
+{ NULL },
+};
+
+static const AVClass class = {
+    .class_name     = "spdif",
+    .item_name      = av_default_item_name,
+    .option         = options,
+    .version        = LIBAVUTIL_VERSION_INT,
+};
+
+static int spdif_header_ac3(AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    int bitstream_mode = pkt->data[5] & 0x7;
+
+    ctx->data_type  = IEC61937_AC3 | (bitstream_mode << 8);
+    ctx->pkt_offset = AC3_FRAME_SIZE << 2;
+    return 0;
+}
+
+static int spdif_header_eac3(AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    static const uint8_t eac3_repeat[4] = {6, 3, 2, 1};
+    int repeat = 1;
+
+    if ((pkt->data[4] & 0xc0) != 0xc0) /* fscod */
+        repeat = eac3_repeat[(pkt->data[4] & 0x30) >> 4]; /* numblkscod */
+
+    ctx->hd_buf = av_fast_realloc(ctx->hd_buf, &ctx->hd_buf_size, ctx->hd_buf_filled + pkt->size);
+    if (!ctx->hd_buf)
+        return AVERROR(ENOMEM);
+
+    memcpy(&ctx->hd_buf[ctx->hd_buf_filled], pkt->data, pkt->size);
+
+    ctx->hd_buf_filled += pkt->size;
+    if (++ctx->hd_buf_count < repeat){
+        ctx->pkt_offset = 0;
+        return 0;
+    }
+    ctx->data_type   = IEC61937_EAC3;
+    ctx->pkt_offset  = 24576;
+    ctx->out_buf     = ctx->hd_buf;
+    ctx->out_bytes   = ctx->hd_buf_filled;
+    ctx->length_code = ctx->hd_buf_filled;
+
+    ctx->hd_buf_count  = 0;
+    ctx->hd_buf_filled = 0;
+    return 0;
+}
+
+/*
+ * DTS type IV (DTS-HD) can be transmitted with various frame repetition
+ * periods; longer repetition periods allow for longer packets and therefore
+ * higher bitrate. Longer repetition periods mean that the constant bitrate of
+ * the outputted IEC 61937 stream is higher.
+ * The repetition period is measured in IEC 60958 frames (4 bytes).
+ */
+static int spdif_dts4_subtype(int period)
+{
+    switch (period) {
+    case 512:   return 0x0;
+    case 1024:  return 0x1;
+    case 2048:  return 0x2;
+    case 4096:  return 0x3;
+    case 8192:  return 0x4;
+    case 16384: return 0x5;
+    }
+    return -1;
+}
+
+static int spdif_header_dts4(AVFormatContext *s, AVPacket *pkt, int core_size,
+                             int sample_rate, int blocks)
+{
+    IEC61937Context *ctx = s->priv_data;
+    static const char dtshd_start_code[10] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfe, 0xfe };
+    int pkt_size = pkt->size;
+    int period;
+    int subtype;
+
+    if (!core_size) {
+        av_log(s, AV_LOG_ERROR, "HD mode not supported for this format\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (!sample_rate) {
+        av_log(s, AV_LOG_ERROR, "Unknown DTS sample rate for HD\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    period = ctx->dtshd_rate * (blocks << 5) / sample_rate;
+    subtype = spdif_dts4_subtype(period);
+
+    if (subtype < 0) {
+        av_log(s, AV_LOG_ERROR, "Specified HD rate of %d Hz would require an "
+               "impossible repetition period of %d for the current DTS stream"
+               " (blocks = %d, sample rate = %d)\n", ctx->dtshd_rate, period,
+               blocks << 5, sample_rate);
+        return AVERROR(EINVAL);
+    }
+
+    /* set pkt_offset and DTS IV subtype according to the requested output
+     * rate */
+    ctx->pkt_offset = period * 4;
+    ctx->data_type = IEC61937_DTSHD | subtype << 8;
+
+    /* If the bitrate is too high for transmitting at the selected
+     * repetition period setting, strip DTS-HD until a good amount
+     * of consecutive non-overflowing HD frames have been observed.
+     * This generally only happens if the caller is cramming a Master
+     * Audio stream into 192kHz IEC 60958 (which may or may not fit). */
+    if (sizeof(dtshd_start_code) + 2 + pkt_size
+            > ctx->pkt_offset - BURST_HEADER_SIZE && core_size) {
+        if (!ctx->dtshd_skip)
+            av_log(s, AV_LOG_WARNING, "DTS-HD bitrate too high, "
+                                      "temporarily sending core only\n");
+        if (ctx->dtshd_fallback > 0)
+            ctx->dtshd_skip = sample_rate * ctx->dtshd_fallback / (blocks << 5);
+        else
+            /* skip permanently (dtshd_fallback == -1) or just once
+             * (dtshd_fallback == 0) */
+            ctx->dtshd_skip = 1;
+    }
+    if (ctx->dtshd_skip && core_size) {
+        pkt_size = core_size;
+        if (ctx->dtshd_fallback >= 0)
+            --ctx->dtshd_skip;
+    }
+
+    ctx->out_bytes   = sizeof(dtshd_start_code) + 2 + pkt_size;
+
+    /* Align so that (length_code & 0xf) == 0x8. This is reportedly needed
+     * with some receivers, but the exact requirement is unconfirmed. */
+    ctx->length_code = FFALIGN(ctx->out_bytes + 0x8, 0x10) - 0x8;
+
+    av_fast_malloc(&ctx->hd_buf, &ctx->hd_buf_size, ctx->out_bytes);
+    if (!ctx->hd_buf)
+        return AVERROR(ENOMEM);
+
+    ctx->out_buf = ctx->hd_buf;
+
+    memcpy(ctx->hd_buf, dtshd_start_code, sizeof(dtshd_start_code));
+    AV_WB16(ctx->hd_buf + sizeof(dtshd_start_code), pkt_size);
+    memcpy(ctx->hd_buf + sizeof(dtshd_start_code) + 2, pkt->data, pkt_size);
+
+    return 0;
+}
+
+static int spdif_header_dts(AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    uint32_t syncword_dts = AV_RB32(pkt->data);
+    int blocks;
+    int sample_rate = 0;
+    int core_size = 0;
+
+    if (pkt->size < 9)
+        return AVERROR_INVALIDDATA;
+
+    switch (syncword_dts) {
+    case DCA_MARKER_RAW_BE:
+        blocks = (AV_RB16(pkt->data + 4) >> 2) & 0x7f;
+        core_size = ((AV_RB24(pkt->data + 5) >> 4) & 0x3fff) + 1;
+        sample_rate = avpriv_dca_sample_rates[(pkt->data[8] >> 2) & 0x0f];
+        break;
+    case DCA_MARKER_RAW_LE:
+        blocks = (AV_RL16(pkt->data + 4) >> 2) & 0x7f;
+        ctx->extra_bswap = 1;
+        break;
+    case DCA_MARKER_14B_BE:
+        blocks =
+            (((pkt->data[5] & 0x07) << 4) | ((pkt->data[6] & 0x3f) >> 2));
+        break;
+    case DCA_MARKER_14B_LE:
+        blocks =
+            (((pkt->data[4] & 0x07) << 4) | ((pkt->data[7] & 0x3f) >> 2));
+        ctx->extra_bswap = 1;
+        break;
+    case DCA_HD_MARKER:
+        /* We only handle HD frames that are paired with core. However,
+           sometimes DTS-HD streams with core have a stray HD frame without
+           core in the beginning of the stream. */
+        av_log(s, AV_LOG_ERROR, "stray DTS-HD frame\n");
+        return AVERROR_INVALIDDATA;
+    default:
+        av_log(s, AV_LOG_ERROR, "bad DTS syncword 0x%x\n", syncword_dts);
+        return AVERROR_INVALIDDATA;
+    }
+    blocks++;
+
+    if (ctx->dtshd_rate)
+        /* DTS type IV output requested */
+        return spdif_header_dts4(s, pkt, core_size, sample_rate, blocks);
+
+    switch (blocks) {
+    case  512 >> 5: ctx->data_type = IEC61937_DTS1; break;
+    case 1024 >> 5: ctx->data_type = IEC61937_DTS2; break;
+    case 2048 >> 5: ctx->data_type = IEC61937_DTS3; break;
+    default:
+        av_log(s, AV_LOG_ERROR, "%i samples in DTS frame not supported\n",
+               blocks << 5);
+        return AVERROR(ENOSYS);
+    }
+
+    /* discard extraneous data by default */
+    if (core_size && core_size < pkt->size) {
+        ctx->out_bytes = core_size;
+        ctx->length_code = core_size << 3;
+    }
+
+    ctx->pkt_offset = blocks << 7;
+
+    if (ctx->out_bytes == ctx->pkt_offset) {
+        /* The DTS stream fits exactly into the output stream, so skip the
+         * preamble as it would not fit in there. This is the case for dts
+         * discs and dts-in-wav. */
+        ctx->use_preamble = 0;
+    } else if (ctx->out_bytes > ctx->pkt_offset - BURST_HEADER_SIZE) {
+        avpriv_request_sample(s, "Unrecognized large DTS frame");
+        /* This will fail with a "bitrate too high" in the caller */
+    }
+
+    return 0;
+}
+
+static const enum IEC61937DataType mpeg_data_type[2][3] = {
+    //     LAYER1                      LAYER2                  LAYER3
+    { IEC61937_MPEG2_LAYER1_LSF, IEC61937_MPEG2_LAYER2_LSF, IEC61937_MPEG2_LAYER3_LSF },//MPEG2 LSF
+    { IEC61937_MPEG1_LAYER1,     IEC61937_MPEG1_LAYER23,    IEC61937_MPEG1_LAYER23 },   //MPEG1
+};
+
+static int spdif_header_mpeg(AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    int version =      (pkt->data[1] >> 3) & 3;
+    int layer   = 3 - ((pkt->data[1] >> 1) & 3);
+    int extension = pkt->data[2] & 1;
+
+    if (layer == 3 || version == 1) {
+        av_log(s, AV_LOG_ERROR, "Wrong MPEG file format\n");
+        return AVERROR_INVALIDDATA;
+    }
+    av_log(s, AV_LOG_DEBUG, "version: %i layer: %i extension: %i\n", version, layer, extension);
+    if (version == 2 && extension) {
+        ctx->data_type  = IEC61937_MPEG2_EXT;
+        ctx->pkt_offset = 4608;
+    } else {
+        ctx->data_type  = mpeg_data_type [version & 1][layer];
+        ctx->pkt_offset = spdif_mpeg_pkt_offset[version & 1][layer];
+    }
+    // TODO Data type dependent info (normal/karaoke, dynamic range control)
+    return 0;
+}
+
+static int spdif_header_aac(AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    AACADTSHeaderInfo hdr;
+    GetBitContext gbc;
+    int ret;
+
+    init_get_bits(&gbc, pkt->data, AAC_ADTS_HEADER_SIZE * 8);
+    ret = avpriv_aac_parse_header(&gbc, &hdr);
+    if (ret < 0) {
+        av_log(s, AV_LOG_ERROR, "Wrong AAC file format\n");
+        return AVERROR_INVALIDDATA;
+    }
+
+    ctx->pkt_offset = hdr.samples << 2;
+    switch (hdr.num_aac_frames) {
+    case 1:
+        ctx->data_type = IEC61937_MPEG2_AAC;
+        break;
+    case 2:
+        ctx->data_type = IEC61937_MPEG2_AAC_LSF_2048;
+        break;
+    case 4:
+        ctx->data_type = IEC61937_MPEG2_AAC_LSF_4096;
+        break;
+    default:
+        av_log(s, AV_LOG_ERROR, "%i samples in AAC frame not supported\n",
+               hdr.samples);
+        return AVERROR(EINVAL);
+    }
+    //TODO Data type dependent info (LC profile/SBR)
+    return 0;
+}
+
+
+/*
+ * It seems Dolby TrueHD frames have to be encapsulated in MAT frames before
+ * they can be encapsulated in IEC 61937.
+ * Here we encapsulate 24 TrueHD frames in a single MAT frame, padding them
+ * to achieve constant rate.
+ * The actual format of a MAT frame is unknown, but the below seems to work.
+ * However, it seems it is not actually necessary for the 24 TrueHD frames to
+ * be in an exact alignment with the MAT frame.
+ */
+#define MAT_FRAME_SIZE          61424
+#define TRUEHD_FRAME_OFFSET     2560
+#define MAT_MIDDLE_CODE_OFFSET  -4
+
+static int spdif_header_truehd(AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    int mat_code_length = 0;
+    const char mat_end_code[16] = { 0xC3, 0xC2, 0xC0, 0xC4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x11 };
+
+    if (!ctx->hd_buf_count) {
+        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 };
+        mat_code_length = sizeof(mat_start_code) + BURST_HEADER_SIZE;
+        memcpy(ctx->hd_buf, mat_start_code, sizeof(mat_start_code));
+
+    } else if (ctx->hd_buf_count == 12) {
+        const char mat_middle_code[12] = { 0xC3, 0xC1, 0x42, 0x49, 0x3B, 0xFA, 0x82, 0x83, 0x49, 0x80, 0x77, 0xE0 };
+        mat_code_length = sizeof(mat_middle_code) + MAT_MIDDLE_CODE_OFFSET;
+        memcpy(&ctx->hd_buf[12 * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + MAT_MIDDLE_CODE_OFFSET],
+               mat_middle_code, sizeof(mat_middle_code));
+    }
+
+    if (pkt->size > TRUEHD_FRAME_OFFSET - mat_code_length) {
+        /* if such frames exist, we'd need some more complex logic to
+         * distribute the TrueHD frames in the MAT frame */
+        avpriv_request_sample(s, "Too large TrueHD frame of %d bytes",
+                              pkt->size);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    memcpy(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length],
+           pkt->data, pkt->size);
+    memset(&ctx->hd_buf[ctx->hd_buf_count * TRUEHD_FRAME_OFFSET - BURST_HEADER_SIZE + mat_code_length + pkt->size],
+           0, TRUEHD_FRAME_OFFSET - pkt->size - mat_code_length);
+
+    if (++ctx->hd_buf_count < 24){
+        ctx->pkt_offset = 0;
+        return 0;
+    }
+    memcpy(&ctx->hd_buf[MAT_FRAME_SIZE - sizeof(mat_end_code)], mat_end_code, sizeof(mat_end_code));
+    ctx->hd_buf_count = 0;
+
+    ctx->data_type   = IEC61937_TRUEHD;
+    ctx->pkt_offset  = 61440;
+    ctx->out_buf     = ctx->hd_buf;
+    ctx->out_bytes   = MAT_FRAME_SIZE;
+    ctx->length_code = MAT_FRAME_SIZE;
+    return 0;
+}
+
+static int spdif_write_header(AVFormatContext *s)
+{
+    IEC61937Context *ctx = s->priv_data;
+
+    switch (s->streams[0]->codec->codec_id) {
+    case AV_CODEC_ID_AC3:
+        ctx->header_info = spdif_header_ac3;
+        break;
+    case AV_CODEC_ID_EAC3:
+        ctx->header_info = spdif_header_eac3;
+        break;
+    case AV_CODEC_ID_MP1:
+    case AV_CODEC_ID_MP2:
+    case AV_CODEC_ID_MP3:
+        ctx->header_info = spdif_header_mpeg;
+        break;
+    case AV_CODEC_ID_DTS:
+        ctx->header_info = spdif_header_dts;
+        break;
+    case AV_CODEC_ID_AAC:
+        ctx->header_info = spdif_header_aac;
+        break;
+    case AV_CODEC_ID_TRUEHD:
+        ctx->header_info = spdif_header_truehd;
+        ctx->hd_buf = av_malloc(MAT_FRAME_SIZE);
+        if (!ctx->hd_buf)
+            return AVERROR(ENOMEM);
+        break;
+    default:
+        av_log(s, AV_LOG_ERROR, "codec not supported\n");
+        return AVERROR_PATCHWELCOME;
+    }
+    return 0;
+}
+
+static int spdif_write_trailer(AVFormatContext *s)
+{
+    IEC61937Context *ctx = s->priv_data;
+    av_freep(&ctx->buffer);
+    av_freep(&ctx->hd_buf);
+    return 0;
+}
+
+static av_always_inline void spdif_put_16(IEC61937Context *ctx,
+                                          AVIOContext *pb, unsigned int val)
+{
+    if (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)
+        avio_wb16(pb, val);
+    else
+        avio_wl16(pb, val);
+}
+
+static int spdif_write_packet(struct AVFormatContext *s, AVPacket *pkt)
+{
+    IEC61937Context *ctx = s->priv_data;
+    int ret, padding;
+
+    ctx->out_buf = pkt->data;
+    ctx->out_bytes = pkt->size;
+    ctx->length_code = FFALIGN(pkt->size, 2) << 3;
+    ctx->use_preamble = 1;
+    ctx->extra_bswap = 0;
+
+    ret = ctx->header_info(s, pkt);
+    if (ret < 0)
+        return ret;
+    if (!ctx->pkt_offset)
+        return 0;
+
+    padding = (ctx->pkt_offset - ctx->use_preamble * BURST_HEADER_SIZE - ctx->out_bytes) & ~1;
+    if (padding < 0) {
+        av_log(s, AV_LOG_ERROR, "bitrate is too high\n");
+        return AVERROR(EINVAL);
+    }
+
+    if (ctx->use_preamble) {
+        spdif_put_16(ctx, s->pb, SYNCWORD1);       //Pa
+        spdif_put_16(ctx, s->pb, SYNCWORD2);       //Pb
+        spdif_put_16(ctx, s->pb, ctx->data_type);  //Pc
+        spdif_put_16(ctx, s->pb, ctx->length_code);//Pd
+    }
+
+    if (ctx->extra_bswap ^ (ctx->spdif_flags & SPDIF_FLAG_BIGENDIAN)) {
+        avio_write(s->pb, ctx->out_buf, ctx->out_bytes & ~1);
+    } else {
+        av_fast_malloc(&ctx->buffer, &ctx->buffer_size, ctx->out_bytes + FF_INPUT_BUFFER_PADDING_SIZE);
+        if (!ctx->buffer)
+            return AVERROR(ENOMEM);
+        ff_spdif_bswap_buf16((uint16_t *)ctx->buffer, (uint16_t *)ctx->out_buf, ctx->out_bytes >> 1);
+        avio_write(s->pb, ctx->buffer, ctx->out_bytes & ~1);
+    }
+
+    /* a final lone byte has to be MSB aligned */
+    if (ctx->out_bytes & 1)
+        spdif_put_16(ctx, s->pb, ctx->out_buf[ctx->out_bytes - 1] << 8);
+
+    ffio_fill(s->pb, 0, padding);
+
+    av_log(s, AV_LOG_DEBUG, "type=%x len=%i pkt_offset=%i\n",
+           ctx->data_type, ctx->out_bytes, ctx->pkt_offset);
+
+    avio_flush(s->pb);
+    return 0;
+}
+
+AVOutputFormat ff_spdif_muxer = {
+    .name              = "spdif",
+    .long_name         = NULL_IF_CONFIG_SMALL("IEC 61937 (used on S/PDIF - IEC958)"),
+    .extensions        = "spdif",
+    .priv_data_size    = sizeof(IEC61937Context),
+    .audio_codec       = AV_CODEC_ID_AC3,
+    .video_codec       = AV_CODEC_ID_NONE,
+    .write_header      = spdif_write_header,
+    .write_packet      = spdif_write_packet,
+    .write_trailer     = spdif_write_trailer,
+    .flags             = AVFMT_NOTIMESTAMPS,
+    .priv_class        = &class,
+};