[FFmpeg-devel] HLS Questions

Sun May 20 18:14:37 EEST 2018

No I’ll give it a try and let you know. 

Since this is just audio (no keyframes) I wouldn’t have thought this would have mattered.

Sent from my iPhone

> On May 7, 2018, at 3:52 PM, Aman Gupta <ffmpeg at tmm1.net> wrote:
> 
> On Wed, May 2, 2018 at 7:59 AM, Ronak Patel <
> ronak2121-at-yahoo.com at ffmpeg.org> wrote:
> 
>> Hi all,
>> 
>> So I’ve noticed that ffmpeg does not always properly follow the number we
>> specify for hls_time when generating hls content.
>> 
>> For example, if we have an MP4/AAC file at 44.1kHz sampling rate, we would
>> expect that specifying 9.75238095238095 (420 frames) would return a
>> manifest with the same exact amount of frames throughout.
>> Instead, we see the AAC encoder vary the amount of frames without any real
>> explanation.
>> 
> 
> Did you try -hls_flags split_by_time ?
> 
> Aman
> 
> 
>> 
>> When we run the following command:
>> 
>> /home/ronakp/bin/ffmpeg -i "${FILE}.mp4" -codec copy -hls_time
>> 9.75238095238095 -hls_segment_type fmp4 -hls_flags single_file+append_list
>> -hls_playlist_type vod "${FILE}_10sec_v7.m3u8"
>> 
>> We get a manifest that looks like so:
>> 
>> #EXTM3U
>> #EXT-X-VERSION:7
>> #EXT-X-TARGETDURATION:10
>> #EXT-X-MEDIA-SEQUENCE:0
>> #EXT-X-PLAYLIST-TYPE:VOD
>> #EXT-X-MAP:URI="bk_acx0_006556_22_32_10sec_v7.m4s",BYTERANGE="738 at 0"
>> #EXT-X-DISCONTINUITY
>> #EXTINF:9.798821,
>> #EXT-X-BYTERANGE:38733 at 738
>> bk_acx0_006556_22_32_10sec_v7.m4s
>> #EXTINF:9.752381,
>> #EXT-X-BYTERANGE:38531 at 39471
>> bk_acx0_006556_22_32_10sec_v7.m4s
>> #EXTINF:9.752381,
>> #EXT-X-BYTERANGE:38616 at 78002
>> bk_acx0_006556_22_32_10sec_v7.m4s
>> #EXTINF:9.752381,
>> #EXT-X-BYTERANGE:38545 at 116618
>> bk_acx0_006556_22_32_10sec_v7.m4s
>> 
>> Notice the first segment there contains 2 more AAC frames...
>> 
>> Now, when we run the following command:
>> 
>> /home/ronakp/bin/ffmpeg -i "${FILE}.mp4" -codec copy -hls_time
>> 0.975238095238095 -hls_segment_type fmp4 -hls_flags single_file+append_list
>> -hls_playlist_type vod "${FILE}_10sec_v7.m3u8"
>> 
>> #EXTM3U
>> #EXT-X-VERSION:7
>> #EXT-X-TARGETDURATION:1
>> #EXT-X-MEDIA-SEQUENCE:0
>> #EXT-X-PLAYLIST-TYPE:VOD
>> #EXT-X-MAP:URI="bk_reco_004353_22_32_1sec_v7.m4s",BYTERANGE="738 at 0"
>> #EXT-X-DISCONTINUITY
>> #EXTINF:0.975238,
>> #EXT-X-BYTERANGE:4110 at 738
>> bk_reco_004353_22_32_1sec_v7.m4s
>> #EXTINF:0.975238,
>> #EXT-X-BYTERANGE:3897 at 4848
>> bk_reco_004353_22_32_1sec_v7.m4s
>> #EXTINF:0.975238,
>> #EXT-X-BYTERANGE:4236 at 8745
>> bk_reco_004353_22_32_1sec_v7.m4s
>> #EXTINF:0.975238,
>> 
>> It seems to have the correct amount of frames everywhere.
>> 
>> Even more bizarre is if we run this command:
>> 
>> /home/ronakp/bin/ffmpeg -i "../${FILE}.mp4" -codec copy -hls_time
>> 9.75238095238095 -hls_segment_filename 'file%03d.ts' -hls_segment_type
>> mpegts -hls_playlist_type vod "${FILE}_10sec_v3.m3u8"
>> 
>> The manifest looks like the following:
>> 
>> #EXTM3U
>> #EXT-X-VERSION:3
>> #EXT-X-TARGETDURATION:10
>> #EXT-X-MEDIA-SEQUENCE:0
>> #EXT-X-PLAYLIST-TYPE:VOD
>> #EXTINF:9.799778,
>> file000.ts
>> #EXTINF:9.706889,
>> file001.ts
>> #EXTINF:9.753333,
>> file002.ts
>> #EXTINF:9.799778,
>> file003.ts
>> #EXTINF:9.753333,
>> file004.ts
>> #EXTINF:9.706889,
>> file005.ts
>> #EXTINF:9.799778,
>> file006.ts
>> 
>> The ts segments do not all have the same size, and seems like ffmpeg is
>> unable to properly honor the supplied time.
>> 
>> And finally, when I run the following command:
>> 
>> /home/ronakp/bin/ffmpeg -i "${FILE}.mp4" -codec copy -f dash
>> -single_file_name "${FILE}_1sec.m4s" -min_seg_duration 975238.095238095
>> -hls_playlist 1 "${FILE}_1sec.mpd"
>> 
>> I get a manifest that looks like:
>> 
>> #EXTM3U
>> #EXT-X-VERSION:6
>> #EXT-X-TARGETDURATION:10
>> #EXT-X-MEDIA-SEQUENCE:1
>> #EXT-X-MAP:URI="bk_reco_004353_22_32_10sec.m4s",BYTERANGE="738 at 0"
>> #EXTINF:9.798821,
>> #EXT-X-BYTERANGE:38996 at 738
>> bk_reco_004353_22_32_10sec.m4s
>> #EXTINF:9.798821,
>> #EXT-X-BYTERANGE:38754 at 39734
>> bk_reco_004353_22_32_10sec.m4s
>> #EXTINF:9.798821,
>> #EXT-X-BYTERANGE:38765 at 78488
>> bk_reco_004353_22_32_10sec.m4s
>> #EXTINF:9.798821,
>> #EXT-X-BYTERANGE:38583 at 117253
>> bk_reco_004353_22_32_10sec.m4s
>> #EXTINF:9.798821,
>> #EXT-X-BYTERANGE:38752 at 155836
>> bk_reco_004353_22_32_10sec.m4s
>> 
>> Where every fragment has 1 extra frame in it.
>> 
>> Can someone please help get this fixed? The fragmentation should have been
>> uniform throughout and exactly the same no matter which options I specify
>> here.
>> 
>> For reference, I'm using the following versions of ffmpeg:
>> 
>> ffmpeg version N-90757-g2fc12f4 Copyright (c) 2000-2018 the FFmpeg
>> developers
>>  built with gcc 4.4.6 (GCC) 20110731 (Red Hat 4.4.6-3)
>>  configuration: --prefix=/home/ronakp/ffmpeg_build
>> --pkg-config-flags=--static --extra-cflags=-I/home/ronakp/ffmpeg_build/include
>> --extra-ldflags=-L/home/ronakp/ffmpeg_build/lib --extra-libs=-lpthread
>> --extra-libs=-lm --bindir=/home/ronakp/bin --enable-gpl --enable-avisynth
>> --enable-libfdk_aac --enable-libmp3lame --enable-libopus --enable-libvorbis
>> --enable-nonfree --enable-libvorbis --enable-version3 --disable-ffplay
>>  libavutil      56. 15.100 / 56. 15.100
>>  libavcodec     58. 19.100 / 58. 19.100
>>  libavformat    58. 13.100 / 58. 13.100
>>  libavdevice    58.  4.100 / 58.  4.100
>>  libavfilter     7. 18.100 /  7. 18.100
>>  libswscale      5.  2.100 /  5.  2.100
>>  libswresample   3.  2.100 /  3.  2.100
>>  libpostproc    55.  2.100 / 55.  2.100
>> 
>> Thanks,
>> 
>> Ronak
>> 
>> _______________________________________________
>> ffmpeg-devel mailing list
>> ffmpeg-devel at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> 
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