Dear maintainer:

I can't build libmedia-convert-perl on a system with 1 CPU because one of
the tests segfaults. However, the program crashing is ffmpeg.

How to reproduce: On a VM with 1 CPU, or booting with GRUB_CMDLINE_LINUX="nr_cpus=1":

apt-get source libmedia-convert-perl
cd libmedia-convert-perl-1.6.1
ffmpeg -loglevel warning -y -i t/testvids/bbb.mp4 -dn -threads 1 -c:v libsvtav1 -r:v 24/1 -crf 25 -speed 4 -preset 4 -c:a libvorbis -b:a 133431 -ar 44100 -t 1 -pix_fmt yuv420p -svtav1-params tune=0:film-grain=8 ./1sec.webm

Output:

Svt[info]: -------------------------------------------
Svt[info]: SVT [version]:	SVT-AV1 Encoder Lib v4.2.0
Svt[info]: SVT [build]  :	GCC 16.2.0	 64 bit
Svt[info]: -------------------------------------------
Svt[info]: Level of Parallelism: 1
Svt[info]: Number of PPCS 74
Svt[info]: [asm level on system : up to avx512icl]
Svt[info]: [asm level selected : up to avx512icl]
Svt[info]: -------------------------------------------
Svt[info]: SVT [config]: main profile	tier (auto)	level (auto)
Svt[info]: SVT [config]: width / height / fps numerator / fps denominator 		: 856 / 480 / 24 / 1
Svt[info]: SVT [config]: bit-depth / color format 					: 8 / YUV420
Svt[info]: SVT [config]: preset / tune / pred struct 					: 4 / VQ / random access
Svt[info]: SVT [config]: gop size / mini-gop size / key-frame type 			: 161 / 32 / key frame
Svt[info]: SVT [config]: BRC mode / rate factor 					: CRF / 25.00
Svt[info]: SVT [config]: AQ mode / Variance Boost 					: 2 / 0
Svt[info]: SVT [config]: film grain synth / denoising / level / adaptive blocksize 	: 1 / 0 / 8 / True
Svt[info]: SVT [config]: sharpness / luminance-based QP bias 				: 0 / 0
Svt[info]: SVT [config]: QP scale compress strength 					: 0
Svt[info]: -------------------------------------------
Segmentation fault

For the upstream authors: Instead of downloading the source for libmedia-convert-perl, the input
file bbb.mp4 can be downloaded from this URL, which is where the package is hosted in salsa:

https://salsa.debian.org/wouter/media-convert/-/blob/main/t/testvids/bbb.mp4?ref_type=heads

Thanks.

Control: tags -1 moreinfo

I'd appreciate a backtrace from gdb since I cannot reproduce it on a
system with more than one CPU.

Cheers

I don't have a lot of experience doing that, let's see if the output
below is useful with several -dbgsym packages installed.

[ Note that temporarily booting with GRUB_CMDLINE_LINUX="nr_cpus=1"
  makes your system to become a single-CPU system very easily ]

Thanks.

#0  svt_circular_buffer_empty_check (bufferPtr=0x0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:134
#1  svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691201fcd0, wrapper_dbl_ptr=0x7f6933191c70) at Codec/./Source/Lib/Codec/sys_resource_manager.c:783
#2  0x00007f6936e22fd5 in lib_svt_encoder_send_error_exit (hComponent=<optimized out>, error_code=4874) at Globals/./Source/Lib/Globals/enc_handle.c:5765
#3  0x00007f6936fd52f0 in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:816
#4  0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#5  svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933191f30) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#6  0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#7  0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#8  svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f69331920c0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#9  0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#10 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#11 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192250) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#12 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#13 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#14 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f69331923e0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#15 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#16 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#17 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192570) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#18 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#19 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#20 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192700) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#21 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#22 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#23 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192890) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#24 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#25 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#26 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192a20) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#27 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#28 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#29 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192bb0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#30 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#31 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#32 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192d40) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#33 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#34 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#35 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933192ed0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#36 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#37 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#38 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933193060) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#39 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#40 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#41 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f69331931f0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#42 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#43 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#44 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933193380) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#45 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#46 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#47 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933193510) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#48 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#49 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#50 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f69331936a0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#51 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#52 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#53 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933193830) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#54 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#55 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#56 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f69331939c0) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#57 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#58 0x00007f6937060b27 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#59 svt_get_empty_object.isra.0 (empty_fifo_ptr=0x7f691f2a0b20, wrapper_dbl_ptr=0x7f6933193b50) at Codec/./Source/Lib/Codec/sys_resource_manager.c:789
#60 0x00007f6936fd478a in svt_aom_picture_manager_kernel_iter (context=0x7f6912052720) at Codec/./Source/Lib/Codec/pic_manager_process.c:625
#61 0x00007f6936e29626 in svt_kernel_dispatcher_run (dispatcher=<optimized out>) at Codec/./Source/Lib/Codec/kernel_dispatch.c:41
#62 svt_av1_enc_send_picture (svt_enc_component=<optimized out>, p_buffer=0x7f6933193cb0) at Globals/./Source/Lib/Globals/enc_handle.c:5633
#63 0x00007f693ed20204 in ?? () from /usr/lib/x86_64-linux-gnu/libavcodec.so.63
#64 0x00007f693e9cec59 in ?? () from /usr/lib/x86_64-linux-gnu/libavcodec.so.63
#65 0x00007f693e9cee65 in avcodec_send_frame () from /usr/lib/x86_64-linux-gnu/libavcodec.so.63
#66 0x0000557e7bfc3003 in encode_frame (of=0x557eb8b06780, ost=ost@entry=0x557eb8b7f080, frame=frame@entry=0x0, pkt=0x7f692c000a80) at src/fftools/ffmpeg_enc.c:644
#67 0x0000557e7bfc34d0 in frame_encode (ost=0x557eb8b7f080, frame=0x0, pkt=<optimized out>) at src/fftools/ffmpeg_enc.c:809
#68 encoder_thread (arg=<optimized out>) at src/fftools/ffmpeg_enc.c:913
#69 0x0000557e7bfded35 in task_wrapper (arg=0x557eb8b79288) at src/fftools/ffmpeg_sched.c:2723
#70 0x00007f693dc9edb8 in ?? () from /usr/lib/x86_64-linux-gnu/libc.so.6
#71 0x00007f693dd1cf98 in ?? () from /usr/lib/x86_64-linux-gnu/libc.so.6

tags 1151006 - moreinfo
thanks

I answered the question that was asked. In fact, I think everybody can
reproduce this with the GRUB trick, so I believe the bug is suitable
to be forwarded upstream.

Thanks.

Control: reassign -1 libsvtav1enc4 4.2.0+dfsg-1

This is in svt_av1. Reassinging.

Cheers

We believe that the bug you reported is fixed in the latest version of
svt-av1, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1151006@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Sebastian Ramacher <sramacher@debian.org> (supplier of updated svt-av1 package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Wed, 21 Oct 2026 09:01:20 +0200
Source: svt-av1
Architecture: source
Version: 4.2.0+dfsg-3
Distribution: unstable
Urgency: medium
Maintainer: Debian Multimedia Maintainers <debian-multimedia@lists.debian.org>
Changed-By: Sebastian Ramacher <sramacher@debian.org>
Closes: 1151006
Changes:
 svt-av1 (4.2.0+dfsg-3) unstable; urgency=medium
 .
   * debian/patches: Apply upstream patch to fix encode on single core systems
     (Closes: #1151006)
Checksums-Sha1:
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 969b45ec7732b5ab6878ecd411ee7fcdf8f60770 9624 svt-av1_4.2.0+dfsg-3.debian.tar.xz
 76913a8d54b22d092da0500b83ff7ca2714f240f 7354 svt-av1_4.2.0+dfsg-3_amd64.buildinfo
Checksums-Sha256:
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 e8fe0d65b8b051b3a279a25b866076b5ce2c07a3b86d41a8ddf31c28689815ad 9624 svt-av1_4.2.0+dfsg-3.debian.tar.xz
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Files:
 ea4fe5ebd09de8820b9a9a567f3b42d5 1645 video optional svt-av1_4.2.0+dfsg-3.dsc
 e771bfac351cfba051ab01a453fd13df 9624 video optional svt-av1_4.2.0+dfsg-3.debian.tar.xz
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