[FFmpeg-trac] #4362(ffmpeg:new): ffmpeg can't extract screenshot from webm if -loop 1 not included, fails silently

[FFmpeg]

#4362: ffmpeg can't extract screenshot from webm if -loop 1 not included, fails
silently
------------------------------------+----------------------------------
             Reporter:  copypaste   |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  ffmpeg
              Version:  git-master  |               Resolution:
             Keywords:  seek        |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
------------------------------------+----------------------------------
Changes (by x-yuri):

 * keywords:   => seek


Comment:

 I think I've run into the same issue:

 {{{
 $ ffmpeg -i _/5.mp4 |& grep Duration
   Duration: 00:00:01.00, start: 0.000000, bitrate: 183 kb/s

 $ ffprobe -show_frames _/5.mp4 |& tail -n 30 | egrep
 'time|duration|FRAME|type'
 [FRAME]
 media_type=video
 pkt_pts_time=0.967633
 pkt_dts_time=N/A
 best_effort_timestamp=29029
 best_effort_timestamp_time=0.967633
 pkt_duration=1001
 pkt_duration_time=0.033367
 pict_type=P
 [/FRAME]

 $ echo 0.967633 + 0.033367 | bc -l
 1.001000

 $ ffmpeg -s 300x300 -c png  -vframes 1 -ss 00:00:00.967650 _/5.mp4.png -i
 _/5.mp4
 ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers
   built with gcc 7.3.0 (GCC)
   configuration: --prefix=/usr --disable-debug --disable-static --disable-
 stripping --enable-avisynth --enable-avresample --enable-fontconfig
 --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libass
 --enable-libbluray --enable-libfreetype --enable-libfribidi --enable-
 libgsm --enable-libiec61883 --enable-libmodplug --enable-libmp3lame
 --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg
 --enable-libopus --enable-libpulse --enable-libsoxr --enable-libspeex
 --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab
 --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264
 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid
 --enable-shared --enable-version3 --enable-omx
   libavutil      55. 78.100 / 55. 78.100
   libavcodec     57.107.100 / 57.107.100
   libavformat    57. 83.100 / 57. 83.100
   libavdevice    57. 10.100 / 57. 10.100
   libavfilter     6.107.100 /  6.107.100
   libavresample   3.  7.  0 /  3.  7.  0
   libswscale      4.  8.100 /  4.  8.100
   libswresample   2.  9.100 /  2.  9.100
   libpostproc    54.  7.100 / 54.  7.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '_/5.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf56.30.100
   Duration: 00:00:01.00, start: 0.000000, bitrate: 183 kb/s
     Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p,
 1920x1080 [SAR 1:1 DAR 16:9], 174 kb/s, 29.97 fps, 29.97 tbr, 30k tbn,
 59.94 tbc (default)
     Metadata:
       handler_name    : VideoHandler
 Stream mapping:
   Stream #0:0 -> #0:0 (h264 (native) -> png (native))
 Press [q] to stop, [?] for help
 Output #0, image2, to '_/5.mp4.png':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf57.83.100
     Stream #0:0(eng): Video: png, rgb24, 300x300 [SAR 16:9 DAR 16:9],
 q=2-31, 200 kb/s, 29.97 fps, 29.97 tbn, 29.97 tbc (default)
     Metadata:
       handler_name    : VideoHandler
       encoder         : Lavc57.107.100 png
 frame=    0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=
 0x
 video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 Output file is empty, nothing was encoded (check -ss / -t / -frames
 parameters if used)
 }}}

 With `-ss 00:00:00.967649` it makes a screenshot. The video is [https
 ://00e9e64bacf49116fd990ea63d02ee36fe53558d81dd6d5ffa-
 apidata.googleusercontent.com/download/storage/v1/b/monorail-
 prod.appspot.com/o/16%2Fattachments%2F1d0b089d-f4c0-4bc9-8e9a-
 f015b1032c11?qk=AD5uMEsOJjvF4bk6cq4VZcqwJQZ4nJeEIxn-
 BLiFvj_ita3YPrvIuldNEjlanE5bVevQG-
 hA8x0Uf2DFXItTCjnAw3QrOhWUv4IHHHA3OMmW9K1nTLfdlQsZqxJ4xfeopioXKVwgXi05XlAKNNCM7yLMIRY7GyOKzj3f51Tt-
 OXCxPwRBzxJu4EREwZoTZ8uPcVV2Nu-
 G_3emknGTdSVjR7InAHhkRKS7aYAO8EerHi6Jss1smpL5wz0mfP22MEOyvmt6JBAqKH1qyMXv8IMJ41gwRBM8cLJCwyJrKFbEdGlBYQOapue73RQz39Rpdf9EJxzWIYegmy-
 _AWIKdbZHXwgLyfr8DAi1BEooCR8NJEDn7RX7WVOpflGKLXRSWBL5l6sUA5IFmZwJXJS6z6kl57y6_V41qX7t0Yp55qJLFNWqFcc6MtJmObUfSTzf8X82zhhqu28x6gkny48TUUtO3MkrOzN6A52Dj40tOPS0MBLA2OO7Mm6wuEWr4K-
 YwvEu-sNaNYnCt-0zCdr8SvjuFE5MFN8VEw-
 DXsmzJ2KEzwZCkfGSCeApGkKhn5bIW9tXxJ_nDFS_Ke7duhMnPbM3PrPZRRm3tQ3XB1PsF26Q_q4e82PZOHWDk1O8u0
 -5WmnNa8Lk3dOif7U1nRg20nYSoDtuXARuimCqg40wCOSawZBFFxhCCFJ_xWMHbuim4qtwBK2QGAUL-
 wkegABCrvYByd4ZkNbPIUSy96PqA4wlR4pab17_3Ii_vCfimrmThpo4m7PQKYhAkqX7w2KWcO0__G12ZIVhmSSGA
 here]

 Feel free to ask for more details.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/4362#comment:2>
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