1.3 KiB
1.3 KiB
Closed Captions
Note:
This is only an experimental feature. Please be aware that bugs and unexpected behavior may occur. To utilize this feature, a version after 7.1 of FFmpeg is required. Importantly, there is currently no official support for this functionality.
Usage
ffplayout can handle closed captions in WebVTT format for HLS streaming.
The captions can be embedded in the file, such as in a Matroska file, or they can be a separate *.vtt file that shares the same filename as the video file. In either case, the processing option vtt_enable must be enabled, and the path to the vtt_dummy file must exist.
To encode the closed captions, the hls mode needs to be enabled, and specific output parameters must be provided. Here’s an example:
-c:v libx264 -crf 23 -x264-params keyint=50:min-keyint=25:scenecut=-1 \
-maxrate 1300k -bufsize 2600k -preset faster -tune zerolatency \
-profile:v Main -level 3.1 -c:a aac -ar 44100 -b:a 128k -flags +cgop \
-muxpreload 0 -muxdelay 0 -f hls -hls_time 6 -hls_list_size 600 \
-hls_flags append_list+delete_segments+omit_endlist \
-var_stream_map v:0,a:0,s:0,sgroup:subs,sname:English,language:en-US,default:YES \
-master_pl_name master.m3u8 \
-hls_segment_filename \
live/stream-%d.ts live/stream.m3u8