Hi,
We are considering using fMP4 assets to power our new audio only streaming. One of our big requirements is to have the ability to deterministically clip the streams at the proper aac frame boundaries. I've noticed that ffmpeg has been getting more stable in how it fragments the source mp4, but it still is not completely consistent. Just a reminder that this stream is audio only, no video, so keyframes and I-frames are not involved. Here's an example that illustrates a problematic manifest: #EXTM3U #EXT-X-VERSION:4 #EXT-X-TARGETDURATION:1 #EXT-X-MEDIA-SEQUENCE:0 #EXT-X-PLAYLIST-TYPE:VOD #EXT-X-DISCONTINUITY #EXTINF:1.021778, #EXT-X-BYTERANGE:9588@0 output_44_64_heaac_1sec_ts.ts #EXTINF:0.928889, #EXT-X-BYTERANGE:7708@9588 output_44_64_heaac_1sec_ts.ts #EXTINF:1.021778, #EXT-X-BYTERANGE:9024@17296 output_44_64_heaac_1sec_ts.ts #EXTINF:0.928889, #EXT-X-BYTERANGE:7896@26320 output_44_64_heaac_1sec_ts.ts #EXTINF:1.021778, #EXT-X-BYTERANGE:9024@34216 output_44_64_heaac_1sec_ts.ts #EXTINF:0.928889, #EXT-X-BYTERANGE:8272@43240 output_44_64_heaac_1sec_ts.ts #EXTINF:0.975333, #EXT-X-BYTERANGE:8272@51512 output_44_64_heaac_1sec_ts.ts #EXTINF:1.021778, #EXT-X-BYTERANGE:8648@59784 output_44_64_heaac_1sec_ts.ts We generated this manifest by running this command: ffmpeg -i output_44_64_heaac.aac -codec copy -hls_time 0.975238095238095 -hls_segment_type mpegts -hls_flags single_file+append_list+split_by_time -hls_playlist_type vod output_44_64_heaac_1sec_ts.m3u8 And here's information about my version of ffmpeg: ffprobe version git-2018-05-06-053ee99 Copyright (c) 2007-2018 the FFmpeg developers built with Apple LLVM version 9.1.0 (clang-902.0.39.1) configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD-053ee99 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libfdk-aac --enable-libmp3lame --enable-libopus --enable-librubberband --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-nonfree libavutil 56. 18.100 / 56. 18.100 libavcodec 58. 19.100 / 58. 19.100 libavformat 58. 13.101 / 58. 13.101 libavdevice 58. 4.100 / 58. 4.100 libavfilter 7. 21.100 / 7. 21.100 libavresample 4. 0. 0 / 4. 0. 0 libswscale 5. 2.100 / 5. 2.100 libswresample 3. 2.100 / 3. 2.100 libpostproc 55. 2.100 / 55. 2.100 Even specifying split_by_time doesn't force ffmpeg to split exactly at the correct amount of AAC frames (42 in this case). Is this a bug in ffmpeg or a limitation of the fMP4 file format? Was this fixed in newer versions? Thanks, Ronak _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
