audio sync & AR problem.

[Nematocyst]

Hi, I'm unable to use vapoursynth because I get two problems. I've not been successful getting audio muxed into the final encode without a progressive sync problem. I don't think it's a strictly mux problem because I've muxed various ways and get the exact same behavior. Also, using vapoursynth, I'm forced to do a resize to get the correct AR, which using ffmpeg is unnecessary. What's causing this?

vapoursynth script:

from vapoursynth import core
video = core.ffms2.Source(source='<foo.mkv>')

# just use a small bit for filter testing
#video = video[0:1800]

# dot-crawl/rainbow elimination
#video = core.tcomb.TComb(video)

# deinterlace
video = core.tdm.TDeintMod(video, 1)

# denoise

# crop
video = core.std.CropAbs(video,704,464,6,10)
video = core.resize.Bicubic(video, 720, 540)

video.set_output()

and finish up with this cmdline followed by audio mux:

vspipe --y4m <foo.vpy> - | ffmpeg -i pipe: -c:v libx265 -preset veryslow -crf 20 -vf "nlmeans=s=10" -y "outfoo.mkv"

ffmpeg commandline that works fine, but lacks comb filter

VCODEC="-c:v libx265 -preset veryslow -crf 20"
FCHAIN='-vf "yadif,nlmeans=s=10,crop=704:464:6:10"'

ffmpeg -i "<foo.mkv>" $VCODEC -c:a copy $FCHAIN -y "<outfoo.mkv>"

[edit]
extra info regarding AR problem. If I use the vapoursynth script above, commenting out the crop+resize and issue this command:

vspipe --y4m <foo.vpy> - | ffplay -i pipe:

I get the wrong AR compared to just:

ffplay -i <foo.mkv>

and this output from the vpy script on the cmdline:

Input #0, yuv4mpegpipe, from 'pipe:':B vq= 0KB sq= 0B f=0/0
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p(progressive), 720x540, 29.64 fps, 29.64 tbr, 29.64 tbn, 29.64 tbc
^C 2.87 M-V: -0.033 fd= 1 aq= 0KB vq=15380KB sq= 0B f=0/0

I don't really understand what it's telling me, but I'm guessing the pipe causes some kind of loss of stream info that the player needs to show it properly.

[sneaker_ger]

If you dumb everything down to

from vapoursynth import core
video = core.ffms2.Source(source='foo.mkv')
video.set_output()

vspipe --y4m "foo.vpy" - | ffmpeg -i pipe: -c:v libx264 -preset ultrafast -y "outfoovideo.mkv"
ffmpeg -i "outfoovideo.mkv" -i "foo.mkv" -map 0:v -map 1:a -c copy "outfoo.mkv"

do you still have sync issues?

[ChaosKing]

29.64 fps looks suspicious, maybe it has VFR?

[Nematocyst]

Originally Posted by sneaker_ger

If you dumb everything down to

from vapoursynth import core
video = core.ffms2.Source(source='foo.mkv')
video.set_output()

vspipe --y4m "foo.vpy" - | ffmpeg -i pipe: -c:v libx264 -preset ultrafast -y "outfoovideo.mkv"
ffmpeg -i "outfoovideo.mkv" -i "foo.mkv" -map 0:v -map 1:a -c copy "outfoo.mkv"

do you still have sync issues?

great question. yes, same exact audio problem.

[Nematocyst]

Originally Posted by ChaosKing

29.64 fps looks suspicious, maybe it has VFR?

MIght be the issue. the source is a title_00x.mkv created with makemkv. vlc's codec info shows it as 29.970030. opening the encoded video in vlc shows it as 29.637534. This is the intermediate file [no audio] from the dumbed down script suggested by sneaker_ger.

[Nematocyst]

Still don't really understand the issue, but maybe the pipe is causing both problems?

Because of warnings about finding stuff when compiling vapoursynth, I use this script for vspipe. Doesn't seem like it should cause problems. but I'm at a loss.

#!/bin/sh
PYTHONPATH="/usr/local/lib/python3.5/site-packages/" LD_LIBRARY_PATH="/usr/local/lib" /usr/local/bin/vspipe $@

Here's the ffmpeg output when creating the intermediate file:

eric@hiarcs:~/Desktop$ !2020
vspipe --y4m "foo.vpy" - | ffmpeg -i pipe: -c:v libx264 -preset ultrafast -y "outfoovideo.mkv"
ffmpeg version 3.3.9 Copyright (c) 2000-2018 the FFmpeg developers
built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516
configuration: --disable-decoder=amrnb --disable-decoder=libopenjpeg --disable-mips32r2 --disable-mips32r6 --disable-mips64r6 --disable-mipsdsp --disable-mipsdspr2 --disable-mipsfpu --disable-msa --disable-libopencv --disable-podpages --disable-stripping --enable-avfilter --enable-avresample --enable-gcrypt --enable-gnutls --enable-gpl --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libkvazaar --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx265 --enable-libxvid --enable-libzvbi --enable-nonfree --enable-opengl --enable-openssl --enable-postproc --enable-pthreads --enable-shared --enable-version3 --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --toolchain=hardened --enable-frei0r --enable-chromaprint --enable-libx264 --enable-libiec61883 --enable-libdc1394 --enable-vaapi --disable-opencl --enable-libmfx --disable-altivec --shlibdir=/usr/lib/x86_64-linux-gnu
libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libavresample 3. 5. 0 / 3. 5. 0
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
Input #0, yuv4mpegpipe, from 'pipe:':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p(progressive), 720x480, 29.64 fps, 29.64 tbr, 29.64 tbn, 29.64 tbc
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
[libx264 @ 0x563cdd535460] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264 @ 0x563cdd535460] profile Constrained Baseline, level 3.0
[libx264 @ 0x563cdd535460] 264 - core 150 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=0 intra_refresh=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=0
Output #0, matroska, to 'outfoovideo.mkv':
Metadata:
encoder : Lavf57.71.100
Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 720x480, q=-1--1, 29.64 fps, 1k tbn, 29.64 tbc
Metadata:
encoder : Lavc57.89.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
^Z
[1]+ Stopped vspipe --y4m "foo.vpy" - | ffmpeg -i pipe: -c:v libx264 -preset ultrafast -y "outfoovideo.mkv"

[lansing]

If the problem is vfr, you should be able to extract the time code from the video.

[Lypheo]

You need to write the timecodes to a file and then mux them into the video.

vspipe --y4m <foo.vpy> --timecodes timecodes.txt - | ffmpeg -i pipe: -c:v libx265 -preset veryslow -crf 20 -vf "nlmeans=s=10" -y "outfoo.mkv"

Then:

mkvmerge --output finalfoo.mkv --timestamps 0:timecodes.txt outfoo.mkv

[Nematocyst]

Originally Posted by Lypheo

You need to write the timecodes to a file and then mux them into the video.

vspipe --y4m <foo.vpy> --timecodes timecodes.txt - | ffmpeg -i pipe: -c:v libx265 -preset veryslow -crf 20 -vf "nlmeans=s=10" -y "outfoo.mkv"

Then:

mkvmerge --output finalfoo.mkv --timestamps 0:timecodes.txt outfoo.mkv

Thank you. I tried this method and it worked fine. I ended up with a video of 30.303030 according to vlc's codec information. But whatever, it looks and sounds right except the AR issue.

[edit]
Fixed the AR issue running:

ffmpeg -i finalfoo.mkv -aspect 720:540 -c copy finalfoo2.mkv

I'm assuming adding "-aspect 720:540" in the encoder line (2nd stage) above would also work.

[Keiyakusha]

Originally Posted by Nematocyst

extra info regarding AR problem. If I use the vapoursynth script above, commenting out the crop+resize and issue this command:

I get the wrong AR compared to just:

and this output from the vpy script on the cmdline:

Image on DVDs is distorted (sorry can't come up with a better word at this time) by design. It is corrected on-playback using whatever information in mkv container or video stream itself. After passing through vapoursynth, correction information is lost (and manual scaling you don't perform). This is all as it should be. You must select correct display ratio for the video when you do encoding, muxing into container or both (since this information would be written in different places: video stream / container)

Edit: also if makemkv is responsible for making initial mkvs, there is no way the fremarate issue would be VFR-related. Correct me if i'm wrong, but makemkv doesn't do re-encoding and can't decimate frames, which is required to produce VFR. So not sure why people are suggesting that.

[jackoneill]

Originally Posted by Keiyakusha

Edit: also if makemkv is responsible for making initial mkvs, there is no way the fremarate issue would be VFR-related. Correct me if i'm wrong, but makemkv doesn't do re-encoding and can't decimate frames, which is required to produce VFR. So not sure why people are suggesting that.

You can have NTSC DVDs where parts of the video are 24000/1001 fps with RFF flags, and parts are 30000/1001 fps.