[FFmpeg-devel] [PATCH] avformat/mpegts: Passthrough SCTE 35 (PR #20342)

[FFmpeg-devel] [PATCH] avformat/mpegts: Passthrough SCTE 35 (PR #20342)

[pierrelefevre via ffmpeg-devel]

PR #20342 opened by pierrelefevre
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20342
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20342.patch

Current behavior breaks SCTE 35 streams by wrapping the data in a PES packet. This MR lets SCTE 35 pass through cleanly without modification.


>From da29faa314e3abc5f325a0988ac1424d8e4a0746 Mon Sep 17 00:00:00 2001
From: Pierre Le Fevre <hello@pierrelf.com>
Date: Wed, 11 Jun 2025 15:25:13 +0200
Subject: [PATCH] avformat/mpegts: Passthrough SCTE 35 Current behavior breaks
 SCTE 35 by wrapping it in a PES packet, this adds the logic for the SCTE 35
 messages to be passed through cleanly.

Signed-off-by: Pierre Le Fevre <hello@pierrelf.com>
---
 libavformat/mpegtsenc.c | 27 +++++++++++++++++++++++++++
 libavformat/mux.c       |  6 ++++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
index 6935b71cfe..ba28e17696 100644
--- a/libavformat/mpegtsenc.c
+++ b/libavformat/mpegtsenc.c
@@ -84,6 +84,7 @@ typedef struct MpegTSWrite {
     MpegTSSection pat; /* MPEG-2 PAT table */
     MpegTSSection sdt; /* MPEG-2 SDT table context */
     MpegTSSection nit; /* MPEG-2 NIT table context */
+    MpegTSSection scte35;
     MpegTSService **services;
     AVPacket *pkt;
     int64_t sdt_period; /* SDT period in PCR time base */
@@ -443,6 +444,9 @@ static int get_dvb_stream_type(AVFormatContext *s, AVStream *st)
             stream_type = STREAM_TYPE_PRIVATE_DATA;
         }
         break;
+    case AV_CODEC_ID_SCTE_35:
+        stream_type = STREAM_TYPE_SCTE_DATA_SCTE_35;
+        break;
     default:
         av_log_once(s, AV_LOG_WARNING, AV_LOG_DEBUG, &ts_st->data_st_warning,
                     "Stream %d, codec %s, is muxed as a private data stream "
@@ -530,6 +534,13 @@ static int mpegts_write_pmt(AVFormatContext *s, MpegTSService *service)
         *q++ = 0xfc;        // private_data_byte
     }
 
+    for (i = 0; i < s->nb_streams; i++) {
+        if(s->streams[i]->codecpar->codec_id==AV_CODEC_ID_SCTE_35) {
+            put_registration_descriptor(&q, MKTAG('C', 'U', 'E', 'I'));
+            break;
+        }
+    }
+
     val = 0xf000 | (q - program_info_length_ptr - 2);
     program_info_length_ptr[0] = val >> 8;
     program_info_length_ptr[1] = val;
@@ -1160,6 +1171,11 @@ static int mpegts_init(AVFormatContext *s)
     ts->nit.write_packet = section_write_packet;
     ts->nit.opaque       = s;
 
+    ts->scte35.cc           = 15;
+    ts->scte35.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
+    ts->scte35.write_packet = section_write_packet;
+    ts->scte35.opaque       = s;
+
     ts->pkt = ffformatcontext(s)->pkt;
 
     /* assign pids to each stream */
@@ -2195,6 +2211,17 @@ static int mpegts_write_packet_internal(AVFormatContext *s, AVPacket *pkt)
         mpegts_write_pes(s, st, buf, size, pts, dts,
                          pkt->flags & AV_PKT_FLAG_KEY, stream_id);
         return 0;
+    } else if (st->codecpar->codec_id == AV_CODEC_ID_SCTE_35) {
+        uint8_t q[1024];
+        unsigned int len;
+
+        len = pkt->size;
+        memcpy(q, pkt->data, len);
+
+        ts->scte35.pid = ts_st->pid;
+        
+        mpegts_write_section(&ts->scte35, q, len);
+        return 0;
     }
 
     if (ts_st->payload_size && (ts_st->payload_size + size > ts->pes_payload_size ||
diff --git a/libavformat/mux.c b/libavformat/mux.c
index db3b6c2bfe..411c9674df 100644
--- a/libavformat/mux.c
+++ b/libavformat/mux.c
@@ -325,7 +325,8 @@ static int init_muxer(AVFormatContext *s, AVDictionary **options)
         }
 
         if (par->codec_type != AVMEDIA_TYPE_ATTACHMENT &&
-            par->codec_id != AV_CODEC_ID_SMPTE_2038)
+            par->codec_id != AV_CODEC_ID_SMPTE_2038 &&
+            par->codec_id != AV_CODEC_ID_SCTE_35)
             fci->nb_interleaved_streams++;
     }
     fci->interleave_packet = of->interleave_packet;
@@ -959,7 +960,8 @@ int ff_interleave_packet_per_dts(AVFormatContext *s, AVPacket *pkt,
         } else if (par->codec_type != AVMEDIA_TYPE_ATTACHMENT &&
                    par->codec_id != AV_CODEC_ID_VP8 &&
                    par->codec_id != AV_CODEC_ID_VP9 &&
-                   par->codec_id != AV_CODEC_ID_SMPTE_2038) {
+                   par->codec_id != AV_CODEC_ID_SMPTE_2038 &&
+                   par->codec_id != AV_CODEC_ID_SCTE_35) {
             ++noninterleaved_count;
         }
     }
-- 
2.49.1

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