This allows having a video stream as reference stream when using the segment muxer:
The video stream serves as a kind of 'heartbeat' to ensure that VTT segments
are generated regularly, even when there aren't any subtitle packets for a
while.
Example:
ffmpeg -i INPUT -map 0:3 -c:0 webvtt -map 0:0 -c:v:0 copy -f segment
-segment_format webvtt -segment_time 6 -write_empty_segments 1 -y
"sub_segment3%d.vtt"
---
libavformat/webvttenc.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/libavformat/webvttenc.c b/libavformat/webvttenc.c index
61b7f54622..be85c03130 100644
--- a/libavformat/webvttenc.c
+++ b/libavformat/webvttenc.c
@@ -49,8 +49,8 @@ static int webvtt_write_header(AVFormatContext *ctx)
AVCodecParameters *par = ctx->streams[0]->codecpar;
AVIOContext *pb = ctx->pb;
- if (ctx->nb_streams != 1 || par->codec_id != AV_CODEC_ID_WEBVTT) {
- av_log(ctx, AV_LOG_ERROR, "Exactly one WebVTT stream is needed.\n");
+ if (par->codec_id != AV_CODEC_ID_WEBVTT) {
+ av_log(ctx, AV_LOG_ERROR, "First stream must be WebVTT.\n");
return AVERROR(EINVAL);
}
@@ -68,6 +68,9 @@ static int webvtt_write_packet(AVFormatContext *ctx, AVPacket
*pkt)
int id_size, settings_size;
uint8_t *id, *settings;
+ if (pkt->stream_index != 0)
+ return 0;
+
avio_printf(pb, "\n");
id = av_packet_get_side_data(pkt, AV_PKT_DATA_WEBVTT_IDENTIFIER,
--
2.17.1.windows.2
0001-libavformat-webvttenc-Allow-but-discard-additional-s.patch
Description: 0001-libavformat-webvttenc-Allow-but-discard-additional-s.patch
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