ffmpeg core dumped error when map webvtt subtitles

[tudge]

ffmpeg giving core dumped, segmentation fault error when adding webvtt subtitles to mapping on any MKV file or Live stream encoding.
Without subtitles all working fine.
Here is the code I use:

./ffmpeg \
-y -vsync 0 -hwaccel cuda -hwaccel_output_format cuda \
-v 9 -loglevel debug \
-report \
-fix_sub_duration \
-i "http://192.168.3.3/any.mkv" \
-map 0:0 -vf scale_cuda=w=1280:h=720 -c:v:0 h264_nvenc -b:v:0 6M \
-map 0:0 -vf scale_cuda=w=1280:h=720 -c:v:1 h264_nvenc -b:v:1 3M \
-map a:0 -c:a:0 aac -b:a:0 128k -ac 2 \
-map a:1 -c:a:1 aac -b:a:1 128k -ac 2 \
-c:s webvtt \
-map s:0 \
-map s:1 \
-f hls \
-hls_time 6 \
-hls_playlist_type event \
-hls_flags independent_segments \
-master_pl_name master.m3u8 \
-hls_segment_type mpegts \
-hls_segment_filename http://192.168.3.3/any/chunk_%02d%v.ts \
-var_stream_map "a:0,agroup:aud,name:rus,language:rus,default:YES a:1,agroup:aud,name:eng,language:English,default:NO v:0,name:1080p,agroup:aud,s:0 v:1,name:720p,agroup:aud,s:1" http://192.168.3.3/any/stream_%v.m3u8

full output with logs in attached file.

[tudge]

full output

[Carl Eugen Hoyos]

Please try to simplify the command line.

[tudge]

Replying to Carl Eugen Hoyos:

Please try to simplify the command line.

sorry, but how simplification will help me?

[Carl Eugen Hoyos]

Replying to tudge:

Replying to Carl Eugen Hoyos:

Please try to simplify the command line.

sorry, but how simplification will help me?

It will help us to understand (and hopefully fix) the issue more easily.

[tudge]

Replying to Carl Eugen Hoyos:

Replying to tudge:

Replying to Carl Eugen Hoyos:

Please try to simplify the command line.

sorry, but how simplification will help me?

It will help us to understand (and hopefully fix) the issue more easily.

Simplified it.

[Carl Eugen Hoyos]

Are cuda and nvenc needed to reproduce? Or is the issue also reproducible with the software scaler and the mpeg2video encoder?

[tudge]

Replying to Carl Eugen Hoyos:

Are cuda and nvenc needed to reproduce? Or is the issue also reproducible with the software scaler and the mpeg2video encoder?

Yes, it is reproducible by software h264/h265 encoders.

[Carl Eugen Hoyos]

Please provide a simplified command line that does not use hardware encoders and no external encoders if possible.

[tudge]

Replying to Carl Eugen Hoyos:

Please provide a simplified command line that does not use hardware encoders and no external encoders if possible.

it worked without scaling in 1 video profile with h264_nvenc encoder. FHD to FHD:

ffmpeg -i any.mkv -c:v h264_nvenc -b:v 5M -map v:0 -c:a aac -b:a 128k -ac 2 -map a:0 -c:s webvtt -map s:1 -f hls -hls_list_size 0 -hls_time 6 -master_pl_name master.m3u8 -var_stream_map "v:0,a:0,agroup:aud,name:English,language:en,default:YES,s:0,sgroup:subs,name:English,language:en,default:YES" /any/stream.m3u8

but subtitles is showing up only on iOS & hlsplayer with delay.

[Carl Eugen Hoyos]

Do I understand correctly that the issue is only reproducible with nvenc?

[tudge]

Replying to Carl Eugen Hoyos:

Do I understand correctly that the issue is only reproducible with nvenc?

It reproducible with any scaling in 2 or more resolutions.

[Carl Eugen Hoyos]

If a command line exists that allows to reproduce the crash without using a hardware encoder please provide this command line.

[tudge]

Replying to Carl Eugen Hoyos:

If a command line exists that allows to reproduce the crash without using a hardware encoder please provide this command line.

./ffmpeg \
-fix_sub_duration \
-i "any.mkv" \
-filter_complex \
"[0:v]yadif,split=4[v1][v2][v3][v4]; \
[v1]scale=w=1920:h=1080[v1out]; \
[v2]scale=w=1280:h=720[v2out]; \
[v3]scale=w=848:h=480[v3out]; \
[v4]scale=w=640:h=360[v4out]" \
-map [v1out] -c:v:0 libx264 -b:v:0 4M -maxrate:v:0 3M -minrate:v:0 3M -bufsize:v:0 6M -preset slow -crf 19 \
-map [v2out] -c:v:1 libx264 -b:v:1 3M -maxrate:v:1 3M -minrate:v:1 1M -bufsize:v:1 6M -preset slow -crf 19 \
-map [v3out] -c:v:2 libx264 -b:v:2 1M -maxrate:v:2 1M -minrate:v:2 1M -bufsize:v:2 2M -preset slow -crf 19 \
-map [v4out] -c:v:3 libx264 -b:v:3 500K -maxrate:v:3 500K -minrate:v:3 500K -bufsize:v:3 1M -preset slow -crf 19 \
-c:a aac \
-map a:0 -b:a:0 128k \
-map a:1 -b:a:1 128k \
-c:s webvtt \
-map s:1 \
-map s:2 \
-f hls \
-hls_time 6 \
-hls_list_size 0 \
-hls_playlist_type vod \
-hls_flags independent_segments \
-master_pl_name master.m3u8 \
-hls_segment_type mpegts \
-hls_segment_filename /any/chunk_%02d%v.ts \
-var_stream_map "a:0,agroup:aud,name:Russian,language:ru,default:YES a:1,agroup:aud,name:EN,language:English,default:NO v:0,name:1080p,agroup:aud,s:0,sgroup:subs,name:Russian,language:ru,default:YES v:1,name:720p,agroup:aud,s:1,sgroup:subs,name:EN,language:English,default:NO v:2,name:480p,agroup:aud v:3,name:360p,agroup:aud" /any/stream_%v.m3u8

[Carl Eugen Hoyos]

Can you also reproduce the crash with the following command line?
./ffmpeg -i "any.mkv" -filter_complex "split[v1out][v2out]" -map [v1out] -map [v2out] -map s:1 -map s:2 -var_stream_map "v:0,s:0 v:1,s:1" /any/stream_%v.m3u8

[Carl Eugen Hoyos]

Looks like a regression since c64d56a2f53455f803456811873ff08fce98e122

[tudge]

Replying to Carl Eugen Hoyos:

Can you also reproduce the crash with the following command line?
./ffmpeg -i "any.mkv" -filter_complex "split[v1out][v2out]" -map [v1out] -map [v2out] -map s:1 -map s:2 -var_stream_map "v:0,s:0 v:1,s:1" /any/stream_%v.m3u8

all the same. Core dumped.

UPD:

master build from MAY 2021 worked fine. Testing it.

[Carl Eugen Hoyos]

Replying to tudge:

Replying to Carl Eugen Hoyos:

Can you also reproduce the crash with the following command line?
./ffmpeg -i "any.mkv" -filter_complex "split[v1out][v2out]" -map [v1out] -map [v2out] -map s:1 -map s:2 -var_stream_map "v:0,s:0 v:1,s:1" /any/stream_%v.m3u8

all the same. Core dumped.

That's what I meant with a "simplified command line".

[Carl Eugen Hoyos]

Crashes for example with:

$ ffmpeg -i any.mkv  -map 0 -var_stream_map "v:0,s:0 v:1,s:1" -vcodec mpeg2video any/stream_%v.m3u8

$ ffmpeg -i any.mkv  -map 0 -var_stream_map "v:0,s:0 v:1,s:1" -vcodec copy any/stream_%v.m3u8

$ ffmpeg -i any.mkv  -map 0 -var_stream_map "v:0,s:0 v:1,s:1" any/stream_%v.m3u8

==217== Invalid read of size 8
==217==    at 0x81E2ED: ff_write_chained (mux.c:1365)
==217==    by 0x7A8C1B: hls_write_packet (hlsenc.c:2669)
==217==    by 0x81F206: write_packet (mux.c:728)
==217==    by 0x81EE61: interleaved_write_packet (mux.c:1102)
==217==    by 0x81EE61: write_packet_common (mux.c:1127)
==217==    by 0x81DD0E: av_interleaved_write_frame (mux.c:1243)
==217==    by 0x40B056: write_packet (ffmpeg_mux.c:174)
==217==    by 0x40A908: sync_queue_process (ffmpeg_mux.c:204)
==217==    by 0x40A908: muxer_thread (ffmpeg_mux.c:235)
==217==    by 0x57A36DA: start_thread (pthread_create.c:463)
==217==    by 0x5ADCA3E: clone (clone.S:95)
==217==  Address 0xd384068 is 8 bytes before a block of size 8 alloc'd
==217==    at 0x4C2FA3F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==217==    by 0x4C31D84: realloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==217==    by 0x84A18F: avformat_new_stream (options.c:250)
==217==    by 0x7AB19C: hls_mux_init (hlsenc.c:889)
==217==    by 0x7AB19C: hls_init (hlsenc.c:3084)
==217==    by 0x81CD66: init_muxer (mux.c:346)
==217==    by 0x81CD66: avformat_init_output (mux.c:433)
==217==    by 0x81D03E: avformat_write_header (mux.c:457)
==217==    by 0x409DD4: of_check_init (ffmpeg_mux.c:478)
==217==    by 0x427D3A: init_output_stream (ffmpeg.c:3292)
==217==    by 0x427D3A: init_output_stream_wrapper (ffmpeg.c:837)
==217==    by 0x428429: do_video_out (ffmpeg.c:1205)
==217==    by 0x4280BA: reap_filters (ffmpeg.c:1427)
==217==    by 0x4214EB: transcode_step (ffmpeg.c:0)
==217==    by 0x4214EB: transcode (ffmpeg.c:4077)
==217==    by 0x41F965: main (ffmpeg.c:4248)
==217==
==217== Invalid read of size 8
==217==    at 0x81E2F5: ff_write_chained (mux.c:1363)
==217==    by 0x7A8C1B: hls_write_packet (hlsenc.c:2669)
==217==    by 0x81F206: write_packet (mux.c:728)
==217==    by 0x81EE61: interleaved_write_packet (mux.c:1102)
==217==    by 0x81EE61: write_packet_common (mux.c:1127)
==217==    by 0x81DD0E: av_interleaved_write_frame (mux.c:1243)
==217==    by 0x40B056: write_packet (ffmpeg_mux.c:174)
==217==    by 0x40A908: sync_queue_process (ffmpeg_mux.c:204)
==217==    by 0x40A908: muxer_thread (ffmpeg_mux.c:235)
==217==    by 0x57A36DA: start_thread (pthread_create.c:463)
==217==    by 0x5ADCA3E: clone (clone.S:95)
==217==  Address 0x10 is not stack'd, malloc'd or (recently) free'd

[tudge]

Is it going to be fixed?

[Steven Liu]

should be fixed by commit 817c6a6762696e6efee44ddc4e2d706922b880e0, Thanks BtbN