[FFmpeg-devel] [PATCH v2] avformat/mpegtsenc: support DVB 6A descriptor for AC-3
lance.lmwang at gmail.com
lance.lmwang at gmail.com
Sat Aug 15 17:27:38 EEST 2020
From: Limin Wang <lance.lmwang at gmail.com>
Signed-off-by: Limin Wang <lance.lmwang at gmail.com>
---
configure | 2 +-
libavformat/mpegts.h | 16 ++++++++++
libavformat/mpegtsenc.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++--
3 files changed, 99 insertions(+), 3 deletions(-)
diff --git a/configure b/configure
index d4a1fea..a9d87b2 100755
--- a/configure
+++ b/configure
@@ -3324,7 +3324,7 @@ mp3_demuxer_select="mpegaudio_parser"
mp3_muxer_select="mpegaudioheader"
mp4_muxer_select="mov_muxer"
mpegts_demuxer_select="iso_media"
-mpegts_muxer_select="adts_muxer latm_muxer h264_mp4toannexb_bsf hevc_mp4toannexb_bsf"
+mpegts_muxer_select="ac3_parser adts_muxer latm_muxer h264_mp4toannexb_bsf hevc_mp4toannexb_bsf"
mpegtsraw_demuxer_select="mpegts_demuxer"
mxf_muxer_select="golomb pcm_rechunk_bsf"
mxf_d10_muxer_select="mxf_muxer"
diff --git a/libavformat/mpegts.h b/libavformat/mpegts.h
index fe10b38..d70b25d 100644
--- a/libavformat/mpegts.h
+++ b/libavformat/mpegts.h
@@ -175,6 +175,22 @@ typedef struct Mp4Descr {
SLConfigDescr sl;
} Mp4Descr;
+/*
+ * ETSI 300 468 descriptor 0x6A(AC-3)
+ * Refer to: ETSI EN 300 468 V1.11.1 (2010-04) (SI in DVB systems)
+ */
+typedef struct DVBAC3Descriptor {
+ uint8_t component_type_flag;
+ uint8_t bsid_flag;
+ uint8_t mainid_flag;
+ uint8_t asvc_flag;
+ uint8_t reserved_flags;
+ uint8_t component_type;
+ uint8_t bsid;
+ uint8_t mainid;
+ uint8_t asvc;
+} DVBAC3Descriptor;
+
/**
* Parse an MPEG-2 descriptor
* @param[in] fc Format context (used for logging only)
diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
index 718ddab..876ba99 100644
--- a/libavformat/mpegtsenc.c
+++ b/libavformat/mpegtsenc.c
@@ -27,6 +27,7 @@
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
+#include "libavcodec/ac3_parser_internal.h"
#include "libavcodec/internal.h"
#include "avformat.h"
@@ -244,6 +245,8 @@ typedef struct MpegTSWriteStream {
/* For Opus */
int opus_queued_samples;
int opus_pending_trim_start;
+
+ DVBAC3Descriptor *dvb_ac3_desc;
} MpegTSWriteStream;
static void mpegts_write_pat(AVFormatContext *s)
@@ -486,9 +489,28 @@ static int mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
case AVMEDIA_TYPE_AUDIO:
if (ts->flags & MPEGTS_FLAG_SYSTEM_B) {
if (codec_id == AV_CODEC_ID_AC3) {
+ DVBAC3Descriptor *dvb_ac3_desc = ts_st->dvb_ac3_desc;
+
*q++=0x6a; // AC3 descriptor see A038 DVB SI
- *q++=1; // 1 byte, all flags sets to 0
- *q++=0; // omit all fields...
+ if (dvb_ac3_desc) {
+ int len = 1 +
+ !!(dvb_ac3_desc->component_type_flag) +
+ !!(dvb_ac3_desc->bsid_flag) +
+ !!(dvb_ac3_desc->mainid_flag) +
+ !!(dvb_ac3_desc->asvc_flag);
+
+ *q++ = len;
+ *q++ = dvb_ac3_desc->component_type_flag << 7 | dvb_ac3_desc->bsid_flag << 6 |
+ dvb_ac3_desc->mainid_flag << 5 | dvb_ac3_desc->asvc_flag << 4;
+
+ if (dvb_ac3_desc->component_type_flag) *q++ = dvb_ac3_desc->component_type;
+ if (dvb_ac3_desc->bsid_flag) *q++ = dvb_ac3_desc->bsid;
+ if (dvb_ac3_desc->mainid_flag) *q++ = dvb_ac3_desc->mainid;
+ if (dvb_ac3_desc->asvc_flag) *q++ = dvb_ac3_desc->asvc;
+ } else {
+ *q++=1; // 1 byte, all flags sets to 0
+ *q++=0; // omit all fields...
+ }
} else if (codec_id == AV_CODEC_ID_EAC3) {
*q++=0x7a; // EAC3 descriptor see A038 DVB SI
*q++=1; // 1 byte, all flags sets to 0
@@ -1843,6 +1865,63 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
* need to count the samples of that too! */
av_log(s, AV_LOG_WARNING, "Got MPEG-TS formatted Opus data, unhandled");
}
+ } else if (st->codecpar->codec_id == AV_CODEC_ID_AC3 && !ts_st->dvb_ac3_desc) {
+ AC3HeaderInfo *hdr = NULL;
+
+ if (avpriv_ac3_parse_header(&hdr, pkt->data, pkt->size) >= 0) {
+ uint8_t number_of_channels_flag;
+ uint8_t service_type_flag;
+ uint8_t full_service_flag = 1;
+ DVBAC3Descriptor *dvb_ac3_desc;
+
+ dvb_ac3_desc = av_mallocz(sizeof(*dvb_ac3_desc));
+ if (!dvb_ac3_desc) {
+ av_free(hdr);
+ return AVERROR(ENOMEM);
+ }
+
+ service_type_flag = hdr->bitstream_mode;
+ switch (hdr->channel_mode) {
+ case AC3_CHMODE_DUALMONO:
+ number_of_channels_flag = 1;
+ break;
+ case AC3_CHMODE_MONO:
+ number_of_channels_flag = 0;
+ break;
+ case AC3_CHMODE_STEREO:
+ if (hdr->dolby_surround_mode == AC3_DSURMOD_ON)
+ number_of_channels_flag = 3;
+ else
+ number_of_channels_flag = 2;
+ break;
+ case AC3_CHMODE_3F:
+ case AC3_CHMODE_2F1R:
+ case AC3_CHMODE_3F1R:
+ case AC3_CHMODE_2F2R:
+ case AC3_CHMODE_3F2R:
+ number_of_channels_flag = 4;
+ break;
+ default: /* reserved */
+ number_of_channels_flag = 7;
+ break;
+ }
+
+ if (service_type_flag == 1 || service_type_flag == 4 ||
+ (service_type_flag == 7 && !number_of_channels_flag))
+ full_service_flag = 0;
+
+ dvb_ac3_desc->component_type_flag = 1;
+ dvb_ac3_desc->component_type = (full_service_flag << 6) |
+ ((service_type_flag & 0x7) << 3) |
+ (number_of_channels_flag & 0x7);
+ dvb_ac3_desc->bsid_flag = 1;
+ dvb_ac3_desc->bsid = hdr->bitstream_id;
+ dvb_ac3_desc->mainid_flag = 0;
+ dvb_ac3_desc->asvc_flag = 0;
+
+ ts_st->dvb_ac3_desc = dvb_ac3_desc;
+ }
+ av_free(hdr);
}
if (ts_st->payload_size && (ts_st->payload_size + size > ts->pes_payload_size ||
@@ -1934,6 +2013,7 @@ static void mpegts_deinit(AVFormatContext *s)
AVStream *st = s->streams[i];
MpegTSWriteStream *ts_st = st->priv_data;
if (ts_st) {
+ av_freep(&ts_st->dvb_ac3_desc);
av_freep(&ts_st->payload);
if (ts_st->amux) {
avformat_free_context(ts_st->amux);
--
1.8.3.1
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