I'm using ffmpeg to generate an HLS stream from a tv tuner capture card,
and while it generates the sub-streams nicely, it seems that the two
streams get out of sync pretty quickly for some stations. What I mean by
that is the segments numbers (and the EXT-X-MEDIA-SEQUENCE) differ. When
the iPhone decides to switch from one to the other, it will "hang" for
several seconds before resuming. It seems (hard to reproduce because it
almost always gets out of sync) shows that it doesn't do that when the
EXT-X-MEDIA-SEQUENCE is the same between the sub-streams.
The test command is:
ffmpeg -f lavfi -i
movie=/dev/dvb/adapter3/dvr0:f=mpegts:s=dv+da[out0+subcc][out1]
-force_key_frames expr:gte(t,n_forced*2) -c:v libx264 -vprofile baseline
-vf scale=1280:720 -s 1280x720 -aspect 1280:720 -pix_fmt yuv420p -r 30
-preset veryfast -b:v 1200k -c:a libfaac -ar 48000 -ac 2 -async 2 -af
volume=volume=11dB -flags:a -global_header -f hls -hls_time 2
-hls_list_size 10 -hls_wrap 20000 -hls_flags delete_segments
-hls_segment_filename /var/www/html/stream/wfgc/v.mid.%d.ts -y
/var/www/html/stream/wfgc/v.mid.m3u8 -force_key_frames
expr:gte(t,n_forced*2) -c:v libx264 -vprofile baseline -vf scale=640:360
-s 640x360 -aspect 640:360 -pix_fmt yuv420p -r 30 -preset veryfast -b:v
200k -c:a libfaac -b:a 50k -ar 24000 -ac 1 -async 2 -af
volume=volume=11dB -flags:a -global_header -f hls -hls_time 2
-hls_list_size 10 -hls_wrap 2000 -hls_flags delete_segments
-hls_segment_filename /var/www/html/stream/wfgc/v.portrait.%d.ts -y
/var/www/html/stream/wfgc/v.portrait.m3u8
I can provide console output, but I've not seen anything useful after
piles of output.
I'm guessing that chopping into 2 second segments, then passing to be
scale/encode in two sub-streams (instead of two sub-streams chopping
into 2 second segments) would solve the problem but I don't know of any
way to do that except write an libav* app?
Any suggestions?
Deron
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