[FFmpeg-user] x264 decimate modifier

[Sebastian Iglesias]

Thanks Lou

I'm adding a text only "cleaner" version of my original request to facilitate the reading:

"Hi

I'm using the following ffmpeg command line as part of a script to generate an H264 1920x1080 representation using the x264 library. I need to create a file with specific x264 opts/params. Until now all the modifiers worked fine, but there is an issue while trying to use the "no-dct-decimate" flag.

This is the command line and the resulting x264 options without using the "no-dct-decimate" flag. (decimate=1)

ffmpeg -threads "24" -i "$2" $DURATION -r 25/1 -g 50 -keyint_min 23 -crf 19 -threads 24 -me_range 32 -me_method umh -subq 10 -sc_threshold 0 -refs 4 -bf 3 -s $FC_PARAM_extra3 -f mp4 -c:v libx264 -x264-params psy-rd=1.00,0.15:b-pyramid=0:b-adapt=2:8x8dct=1:direct=auto:weightb=1:weightp=2:mbtree=1:qcomp=0.75:qpmin=10:qpmax=51:aq-mode=1:aq-strength=0.80:partitions=p8x8+b8x8+i8x8+i4x4:lookahead-threads=6:subme=10:trellis=2:fast-pskip=1 -rc-lookahead 50 -flags +loop -deblock 0:0 -b:v $FC_PARAM_extra4"k" -maxrate $FC_PARAM_extra4"k" -bufsize $FC_PARAM_extra5"k" -level "$FC_PARAM_extra2" -profile:v "$FC_PARAM_extra1" -movflags +write_colr+faststart -c:a libfaac -ac 2 -ab 128k -ar 48000 -cutoff 18000 -pix_fmt yuv420p -vf "[in]yadif=0:-1:0[cc]"$CROP";[cc]scale="$FC_PARAM_extra3[out] $TARGETASPECTRATIO -y "$3”

Resulting in the following x264 options:

[libx264 @ 0x147dfc0] 264 - core 144 r2525 40bb568 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=4 deblock=1:0:0 analyse=0x3:0x113 me=umh subme=10 psy=1 psy_rd=1.00:0.15 mixed_ref=1 me_range=32 chroma_me=1 trellis=2 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-3 threads=24 lookahead_threads=6 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=0 b_adapt=2 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=50 keyint_min=23 scenecut=0 intra_refresh=0 rc_lookahead=50 rc=crf mbtree=1 crf=19.0 qcomp=0.75 qpmin=10 qpmax=51 qpstep=4 vbv_maxrate=5000 vbv_bufsize=10000 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:0.80

And this is the variation while trying to activate the "no-dct-decimate" flag and its results:

Command line

ffmpeg -threads "24" -i "$2" $DURATION -r 25/1 -g 50 -keyint_min 23 -crf 19 -threads 24 -me_range 32 -me_method umh -subq 10 -sc_threshold 0 -refs 4 -bf 3 -s $FC_PARAM_extra3 -f mp4 -c:v libx264 -x264-params psy-rd=1.00,0.15:b-pyramid=0:b-adapt=2:8x8dct=1:direct=auto:weightb=1:weightp=2:mbtree=1:qcomp=0.75:qpmin=10:qpmax=51:aq-mode=1:aq-strength=0.80:partitions=p8x8+b8x8+i8x8+i4x4:lookahead-threads=6:subme=10:trellis=2:fast-pskip=1:no-dct-decimate -rc-lookahead 50 -flags +loop -deblock 0:0 -b:v $FC_PARAM_extra4"k" -maxrate $FC_PARAM_extra4"k" -bufsize $FC_PARAM_extra5"k" -level "$FC_PARAM_extra2" -profile:v "$FC_PARAM_extra1" -c:a libfaac -ac 2 -ab 128k -ar 48000 -cutoff 18000 -pix_fmt yuv420p -vf "[in]yadif=0:-1:0[cc]"$CROP";[cc]scale="$FC_PARAM_extra3[out] $TARGETASPECTRATIO -y "$3"

Resulting in the following x264 options

[libx264 @ 0x835320] 264 - core 144 r2525 40bb568 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=4 deblock=1:0:0 analyse=0x3:0x113 me=umh subme=9 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=32 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=24 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=50 keyint_min=23 scenecut=0 intra_refresh=0 rc_lookahead=50 rc=crf mbtree=1 crf=19.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=5000 vbv_bufsize=10000 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00


As you can see, even while using the flag/modifier. The decimate value stays as "decimate=1" and it also alters other enconding parameters as "qcomp, qpmin, qpmax, aq, etc"

Do you know why is this happening, Am I using another flag which alters the function of the "no-dct-decimate" modifier?

Let me know if any other log/information is needed. Any help is greatly appreciated.

Thanks





El Martes, 15 de marzo, 2016 20:57:50, Lou <lou at lrcd.com> escribió:
On Tue, 15 Mar 2016 19:49:09 +0000 (UTC)
Sebastian Iglesias <cartero33-at-yahoo.com at ffmpeg.org> wrote:

> Thanks for your reply Lou,
> I formatted it differently and with clear spacing. Unfortunately it
> must have been modified while submitting. Is there any way to edit
> the original message? Or do you suggest to delete and re-upload?
> Thanks for your help 

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