S/PDIF demuxer

Patch by Anssi Hannula, anssi d hannula a iki d fi

Originally committed as revision 25804 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 236 insertions, 0 deletions

diff --git a/libavformat/spdifdec.c b/libavformat/spdifdec.c
new file mode 100644
index 0000000000..81e94e7ef1
--- /dev/null
+++ b/libavformat/spdifdec.c
@@ -0,0 +1,236 @@
+/*
+ * IEC 61937 demuxer
+ * Copyright (c) 2010 Anssi Hannula <anssi.hannula at iki.fi>
+ *
+ * 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 demuxer, used for compressed data in S/PDIF
+ * @author Anssi Hannula
+ */
+
+#include "avformat.h"
+#include "spdif.h"
+#include "libavcodec/ac3.h"
+#include "libavcodec/aacadtsdec.h"
+
+static int spdif_get_offset_and_codec(AVFormatContext *s,
+                                      enum IEC958DataType data_type,
+                                      const char *buf, int *offset,
+                                      enum CodecID *codec)
+{
+    AACADTSHeaderInfo aac_hdr;
+    GetBitContext gbc;
+
+    switch (data_type & 0xff) {
+    case IEC958_AC3:
+        *offset = AC3_FRAME_SIZE << 2;
+        *codec = CODEC_ID_AC3;
+        break;
+    case IEC958_MPEG1_LAYER1:
+        *offset = spdif_mpeg_pkt_offset[1][0];
+        *codec = CODEC_ID_MP1;
+        break;
+    case IEC958_MPEG1_LAYER23:
+        *offset = spdif_mpeg_pkt_offset[1][0];
+        *codec = CODEC_ID_MP3;
+        break;
+    case IEC958_MPEG2_EXT:
+        *offset = 4608;
+        *codec = CODEC_ID_MP3;
+        break;
+    case IEC958_MPEG2_AAC:
+        init_get_bits(&gbc, buf, AAC_ADTS_HEADER_SIZE * 8);
+        if (ff_aac_parse_header(&gbc, &aac_hdr)) {
+            if (s) /* be silent during a probe */
+                av_log(s, AV_LOG_ERROR, "Invalid AAC packet in IEC 61937\n");
+            return AVERROR_INVALIDDATA;
+        }
+        *offset = aac_hdr.samples << 2;
+        *codec = CODEC_ID_AAC;
+        break;
+    case IEC958_MPEG2_LAYER1_LSF:
+        *offset = spdif_mpeg_pkt_offset[0][0];
+        *codec = CODEC_ID_MP1;
+        break;
+    case IEC958_MPEG2_LAYER2_LSF:
+        *offset = spdif_mpeg_pkt_offset[0][1];
+        *codec = CODEC_ID_MP2;
+        break;
+    case IEC958_MPEG2_LAYER3_LSF:
+        *offset = spdif_mpeg_pkt_offset[0][2];
+        *codec = CODEC_ID_MP3;
+        break;
+    case IEC958_DTS1:
+        *offset = 2048;
+        *codec = CODEC_ID_DTS;
+        break;
+    case IEC958_DTS2:
+        *offset = 4096;
+        *codec = CODEC_ID_DTS;
+        break;
+    case IEC958_DTS3:
+        *offset = 8192;
+        *codec = CODEC_ID_DTS;
+        break;
+    default:
+        if (s) { /* be silent during a probe */
+            av_log(s, AV_LOG_WARNING, "Data type 0x%04x", data_type);
+            av_log_missing_feature(s, " in IEC 61937 is", 1);
+        }
+        return AVERROR_PATCHWELCOME;
+    }
+    return 0;
+}
+
+/* Largest offset between bursts we currently handle, i.e. AAC with
+   aac_hdr.samples = 4096 */
+#define SPDIF_MAX_OFFSET 16384
+
+static int spdif_probe(AVProbeData *p)
+{
+    const uint8_t *buf = p->buf;
+    const uint8_t *probe_end = p->buf + FFMIN(2 * SPDIF_MAX_OFFSET, p->buf_size - 1);
+    const uint8_t *expected_code = buf + 7;
+    uint32_t state = 0;
+    int sync_codes = 0;
+    int consecutive_codes = 0;
+    int offset;
+    enum CodecID codec;
+
+    for (; buf < probe_end; buf++) {
+        state = (state << 8) | *buf;
+
+        if (state == (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))
+                && buf[1] < 0x37) {
+            sync_codes++;
+
+            if (buf == expected_code) {
+                if (++consecutive_codes >= 2)
+                    return AVPROBE_SCORE_MAX;
+            } else
+                consecutive_codes = 0;
+
+            if (buf + 4 + AAC_ADTS_HEADER_SIZE > p->buf + p->buf_size)
+                break;
+
+            /* continue probing to find more sync codes */
+            probe_end = FFMIN(buf + SPDIF_MAX_OFFSET, p->buf + p->buf_size - 1);
+
+            /* skip directly to the next sync code */
+            if (!spdif_get_offset_and_codec(NULL, (buf[2] << 8) | buf[1],
+                                            &buf[5], &offset, &codec)) {
+                if (buf + offset >= p->buf + p->buf_size)
+                    break;
+                expected_code = buf + offset;
+                buf = expected_code - 7;
+            }
+        }
+    }
+
+    if (!sync_codes)
+        return 0;
+
+    if (sync_codes >= 6)
+        /* good amount of sync codes but with unexpected offsets */
+        return AVPROBE_SCORE_MAX / 2;
+
+    /* some sync codes were found */
+    return AVPROBE_SCORE_MAX / 8;
+}
+
+static int spdif_read_header(AVFormatContext *s, AVFormatParameters *ap)
+{
+    s->ctx_flags |= AVFMTCTX_NOHEADER;
+    return 0;
+}
+
+static int spdif_read_packet(AVFormatContext *s, AVPacket *pkt)
+{
+    ByteIOContext *pb = s->pb;
+    enum IEC958DataType data_type;
+    enum CodecID codec_id;
+    uint32_t state = 0;
+    int pkt_size_bits, offset, ret;
+
+    while (state != (AV_BSWAP16C(SYNCWORD1) << 16 | AV_BSWAP16C(SYNCWORD2))) {
+        state = (state << 8) | get_byte(pb);
+        if (url_feof(pb))
+            return AVERROR_EOF;
+    }
+
+    data_type = get_le16(pb);
+    pkt_size_bits = get_le16(pb);
+
+    if (pkt_size_bits % 16)
+        av_log_ask_for_sample(s, "Packet does not end to a 16-bit boundary.");
+
+    ret = av_new_packet(pkt, FFALIGN(pkt_size_bits, 16) >> 3);
+    if (ret)
+        return ret;
+
+    pkt->pos = url_ftell(pb) - BURST_HEADER_SIZE;
+
+    if (get_buffer(pb, pkt->data, pkt->size) < pkt->size) {
+        av_free_packet(pkt);
+        return AVERROR_EOF;
+    }
+    ff_spdif_bswap_buf16((uint16_t *)pkt->data, (uint16_t *)pkt->data, pkt->size >> 1);
+
+    ret = spdif_get_offset_and_codec(s, data_type, pkt->data,
+                                     &offset, &codec_id);
+    if (ret) {
+        av_free_packet(pkt);
+        return ret;
+    }
+
+    /* skip over the padding to the beginning of the next frame */
+    url_fskip(pb, offset - pkt->size - BURST_HEADER_SIZE);
+
+    if (!s->nb_streams) {
+        /* first packet, create a stream */
+        AVStream *st = av_new_stream(s, 0);
+        if (!st) {
+            av_free_packet(pkt);
+            return AVERROR(ENOMEM);
+        }
+        st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
+        st->codec->codec_id = codec_id;
+    } else if (codec_id != s->streams[0]->codec->codec_id) {
+        av_log_missing_feature(s, "codec change in IEC 61937", 0);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    if (!s->bit_rate && s->streams[0]->codec->sample_rate)
+        /* stream bitrate matches 16-bit stereo PCM bitrate for currently
+           supported codecs */
+        s->bit_rate = 2 * 16 * s->streams[0]->codec->sample_rate;
+
+    return 0;
+}
+
+AVInputFormat spdif_demuxer = {
+    "spdif",
+    NULL_IF_CONFIG_SMALL("IEC 61937 (compressed data in S/PDIF)"),
+    0,
+    spdif_probe,
+    spdif_read_header,
+    spdif_read_packet,
+    .flags = AVFMT_GENERIC_INDEX,
+};