[FFmpeg-user] Segmentation fault for two-pass libx264, but not two-pass libx265
Ferdi Scholten
ferdi at sttc-nlp.nl
Tue Feb 27 17:39:04 EET 2024
I believe this should be a viable routine for two-pass encoding using
libx264, but it fails, as shown. A similar command to encode the same
video source file using libx265 with Matroska output is successful, so I
don’t think the source file is the culprit. Both the x264 and x265
encoding report 1475 frames encoded. Please help. Thanks.
> Sincerely,
> L. Lee
>
> ffmpeg -i ~/Downloads/sgd.ts -map 0:0 -c:v:0 libx264 -b:v 2500k -pass 1 -vf fieldmatch=order=tff:combmatch=none,decimate,crop=1920:1072:0:4 -map 0:1 -an -f null /dev/null && ffmpeg -i ~/Downloads/sgd.ts -map 0:0 -c:v:0 libx264 -b:v 2500k -pass 2 -vf fieldmatch=order=tff:combmatch=none,decimate,crop=1920:1072:0:4 -map 0:1 -c:a ac3 -b:a 384k -movflags +faststart ~/Downloads/sgd.mp4
> ffmpeg version 6.1.1 Copyright (c) 2000-2023 the FFmpeg developers
> built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
> configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_3 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
> libavutil 58. 29.100 / 58. 29.100
> libavcodec 60. 31.102 / 60. 31.102
> libavformat 60. 16.100 / 60. 16.100
> libavdevice 60. 3.100 / 60. 3.100
> libavfilter 9. 12.100 / 9. 12.100
> libswscale 7. 5.100 / 7. 5.100
> libswresample 4. 12.100 / 4. 12.100
> libpostproc 57. 3.100 / 57. 3.100
> Input #0, mpegts, from '/Users/llee/Downloads/sgd.ts':
> Duration: 00:01:02.11, start: 1.400000, bitrate: 14865 kb/s
> Program 1
> Metadata:
> service_name : Service01
> service_provider: FFmpeg
> Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 30 fps, 30 tbr, 90k tbn
> Stream #0:1[0x101]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 640 kb/s
> Stream mapping:
> Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
> Press [q] to stop, [?] for help
> [libx264 @ 0x13c605d00] using SAR=1/1
> [libx264 @ 0x13c605d00] using cpu capabilities: ARMv8 NEON
> [libx264 @ 0x13c605d00] profile Main, level 4.0, 4:2:0, 8-bit
> Output #0, null, to '/dev/null':
> Metadata:
> encoder : Lavf60.16.100
> Stream #0:0: Video: h264, yuv420p(tv, bt709, progressive), 1920x1072 [SAR 1:1 DAR 120:67], q=2-31, 2500 kb/s, 24 fps, 24 tbn
> Metadata:
> encoder : Lavc60.31.102 libx264
> Side data:
> cpb: bitrate max/min/avg: 0/0/2500000 buffer size: 0 vbv_delay: N/A
> [out#0/null @ 0x6000004ac180] video:20127kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
> frame= 1475 fps= 93 q=-1.0 Lsize=N/A time=00:01:01.37 bitrate=N/A speed=3.87x
> [libx264 @ 0x13c605d00] frame I:26 Avg QP:20.39 size: 77028
> [libx264 @ 0x13c605d00] frame P:450 Avg QP:23.72 size: 23644
> [libx264 @ 0x13c605d00] frame B:999 Avg QP:25.04 size: 7975
> [libx264 @ 0x13c605d00] consecutive B-frames: 9.0% 1.4% 2.0% 87.6%
> [libx264 @ 0x13c605d00] mb I I16..4: 64.1% 0.0% 35.9%
> [libx264 @ 0x13c605d00] mb P I16..4: 33.0% 0.0% 0.0% P16..4: 34.8% 0.0% 0.0% 0.0% 0.0% skip:32.2%
> [libx264 @ 0x13c605d00] mb B I16..4: 5.5% 0.0% 0.0% B16..8: 19.6% 0.0% 0.0% direct: 9.1% skip:65.8% L0:39.4% L1:54.2% BI: 6.4%
> [libx264 @ 0x13c605d00] final ratefactor: 24.22
> [libx264 @ 0x13c605d00] coded y,uvDC,uvAC intra: 29.9% 40.3% 6.3% inter: 6.1% 10.3% 0.0%
> [libx264 @ 0x13c605d00] i16 v,h,dc,p: 35% 23% 26% 17%
> [libx264 @ 0x13c605d00] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 24% 20% 22% 3% 9% 6% 6% 5% 5%
> [libx264 @ 0x13c605d00] i8c dc,h,v,p: 56% 20% 21% 3%
> [libx264 @ 0x13c605d00] Weighted P-Frames: Y:2.0% UV:0.9%
> [libx264 @ 0x13c605d00] kb/s:2682.78
> ffmpeg version 6.1.1 Copyright (c) 2000-2023 the FFmpeg developers
> built with Apple clang version 15.0.0 (clang-1500.1.0.2.5)
> configuration: --prefix=/opt/homebrew/Cellar/ffmpeg/6.1.1_3 --enable-shared --enable-pthreads --enable-version3 --cc=clang --host-cflags= --host-ldflags='-Wl,-ld_classic' --enable-ffplay --enable-gnutls --enable-gpl --enable-libaom --enable-libaribb24 --enable-libbluray --enable-libdav1d --enable-libharfbuzz --enable-libjxl --enable-libmp3lame --enable-libopus --enable-librav1e --enable-librist --enable-librubberband --enable-libsnappy --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r --enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopenvino --enable-libspeex --enable-libsoxr --enable-libzmq --enable-libzimg --disable-libjack --disable-indev=jack --enable-videotoolbox --enable-audiotoolbox --enable-neon
> libavutil 58. 29.100 / 58. 29.100
> libavcodec 60. 31.102 / 60. 31.102
> libavformat 60. 16.100 / 60. 16.100
> libavdevice 60. 3.100 / 60. 3.100
> libavfilter 9. 12.100 / 9. 12.100
> libswscale 7. 5.100 / 7. 5.100
> libswresample 4. 12.100 / 4. 12.100
> libpostproc 57. 3.100 / 57. 3.100
> Input #0, mpegts, from '/Users/llee/Downloads/sgd.ts':
> Duration: 00:01:02.11, start: 1.400000, bitrate: 14865 kb/s
> Program 1
> Metadata:
> service_name : Service01
> service_provider: FFmpeg
> Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 30 fps, 30 tbr, 90k tbn
> Stream #0:1[0x101]: Audio: ac3 (AC-3 / 0x332D4341), 48000 Hz, 5.1(side), fltp, 640 kb/s
> Stream mapping:
> Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
> Stream #0:1 -> #0:1 (ac3 (native) -> ac3 (native))
> Press [q] to stop, [?] for help
> [libx264 @ 0x159f07480] using SAR=1/1
> [libx264 @ 0x159f07480] using cpu capabilities: ARMv8 NEON
> [libx264 @ 0x159f07480] profile High, level 4.0, 4:2:0, 8-bit
> [libx264 @ 0x159f07480] 264 - core 164 r3108 31e19f9 - H.264/MPEG-4 AVC codec - Copyleft 2003-2023 -http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=15 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=250 keyint_min=24 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=2pass mbtree=1 bitrate=2500 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 cplxblur=20.0 qblur=0.5 ip_ratio=1.40 aq=1:1.00
> Output #0, mp4, to '/Users/llee/Downloads/sgd.mp4':
> Metadata:
> encoder : Lavf60.16.100
> Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1072 [SAR 1:1 DAR 120:67], q=2-31, 2500 kb/s, 24 fps, 12288 tbn
> Metadata:
> encoder : Lavc60.31.102 libx264
> Side data:
> cpb: bitrate max/min/avg: 0/0/2500000 buffer size: 0 vbv_delay: N/A
> Stream #0:1: Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, 5.1(side), fltp, 384 kb/s
> Metadata:
> encoder : Lavc60.31.102 ac3
> [libx264 @ 0x159f07480] 2nd pass has more frames than 1st pass (1475)720.9kbits/s dup=15 drop=0 speed=3.88x
> [libx264 @ 0x159f07480] continuing anyway, at constant QP=26
> [libx264 @ 0x159f07480] disabling adaptive B-frames
> [1] 63630 segmentation fault ffmpeg -i ~/Downloads/sgd.ts -map 0:0 -c:v:0 libx264 -b:v 2500k -pass 2 -vf
>
>
>
> Looks a bit like this trac ticket I made:https://trac.ffmpeg.org/ticket/10164 which is stiil open after 13 months. The difference in this ticket is that it happens when doing dual pass av1 transcode with libaom. Not always with every file, but very reliably with certain files that always deliver the segfault. I can supply these files, but since the ticket does not get any attention I have not done this yet.
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