[FFmpeg-devel] Adding Webvtt in hls muxer

[Deron]

On 2/21/15 8:05 AM, Deron wrote:
> On 2/15/15 5:44 AM, Anshul wrote:
>>
>> attached another cleaned patch.
>>
>> -Anshul
>
> Not sure if I should be posting here, privately, or do the user list 
> since it is an unaccepted patch... This patch applies cleanly to 
> ffmpeg git of that day, and with minor adjustment to current git, but 
> either crashes the same for me right away. Here is the back trace from 
> gdb:
>
>
> Program received signal SIGSEGV, Segmentation fault.
> __GI___libc_realloc (oldmem=0x70, bytes=8) at malloc.c:2977
> 2977    malloc.c: No such file or directory.
> (gdb) bt
> #0  __GI___libc_realloc (oldmem=0x70, bytes=8) at malloc.c:2977
> #1  0x00007ffff7609b99 in avformat_new_stream (s=s at entry=0xe2dbc0, 
> c=c at entry=0x0) at libavformat/utils.c:3655
> #2  0x00007ffff75451c4 in hls_mux_init (s=0x6787c0) at 
> libavformat/hlsenc.c:194
> #3  hls_write_header (s=0x6787c0) at libavformat/hlsenc.c:490
> #4  0x00007ffff75999ec in avformat_write_header (s=s at entry=0x6787c0, 
> options=0x6a9948) at libavformat/mux.c:406
> #5  0x0000000000424c00 in transcode_init () at ffmpeg.c:3096
> #6  0x0000000000407581 in transcode () at ffmpeg.c:3815
> #7  main (argc=13, argv=0x7fffffffe5a8) at ffmpeg.c:4022
>
>
> The command (I've tried all sorts of combinations. If I don't provide 
> a subtitle stream, it does not crash. Otherwise it does. Unpatched can 
> generate a webvtt from the subtitle stream without crashing.)
>
> ffmpeg -loglevel debug -f lavfi -i movie=out.ts\[out0+subcc\] -f hls 
> -hls_segment_filename /var/www/html/stream/kota/v.low.%d.ts 
> -hls_subtitle_path /var/www/html/stream/kota/ -y 
> /var/www/html/stream/kota/v.low.m3u8
>

I did find the problem. The patch does not properly initialize 
hls->vtt_oformat (etc) if you provide the "-hls_segment_filename" 
parameter as I have done.

Deron