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Recently, videos produced by capturing a window on my system using FFmpeg have become choppy/jerky, as if frames have been dropped or duplicated. FFmpeg will sometimes report that a number of frames were dropped when recording began, but not throughout the video. Videos I had recorded a few months ago did not suffer from this. Encoding speed reports to be between 1.0x & 0.996x.

I suspected that the problem might have to do with system performance related to the hard drive. So I cleaned up junk files on my system & defragmented the drive. But the resulting video output did not change.

Reading through this thread, one user recomends recording at 30 fps instead of 60. But I had no problem recording at 60 before.

The dimensions of the window I am recording are 512x448. I record the audio & video in separate FFmpeg processes (this prevents audio drift).

The following is an example portion of a script I use for recording:

ffmpeg -hide_banner -rtbufsize 500M -thread_queue_size 512 -f dshow -ac 1 -i audio="<audio_device>" -c:a pcm_s16le audio-tmp.wav & APID=$!

ffmpeg -hide_banner -rtbufsize 1500M -thread_queue_size 512 -f gdigrab -framerate 60 -i title="<window_name>" -c:v libx264 -preset ultrafast -qp 0 -x264opts keyint="1" video-tmp.mkv

The entire script can be found here.

System specs:

  • HP Pavilion 24-b217c
  • CPU: Intel Core i5-7400T
    • 2.4GHz
    • 4 cores
  • RAM: 12GB
  • GPU (hybrid):
    • NVIDIA GeForce 930MX
    • 2GB dedicated RAM
    • Intel HD Graphics 630

Edit: Here is the video output from the terminal:

Input #0, gdigrab, from 'title=Mega Man Unlimited':
  Duration: N/A, start: 1550055137.876177, bitrate: 440427 kb/s
    Stream #0:0: Video: bmp, bgra, 512x448, 440427 kb/s, 60 fps, 60 tbr, 1000k tbn, 1000k tbc
Stream mapping:
  Stream #0:0 -> #0:0 (bmp (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 000001d2881a15c0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 000001d2881a15c0] profile High 4:4:4 Intra, level 3.1, 4:4:4, 8-bit
[libx264 @ 000001d2881a15c0] 264 - core 157 r2935 545de2f - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=0 ref=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=0 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=0 chroma_qp_offset=0 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=1 keyint_min=1 scenecut=0 intra_refresh=0 rc=cqp mbtree=0 qp=0
Output #0, matroska, to 'C:/users/antum/Videos/Captures/output-2019-02-13_10.52.17.456113800-video.mkv':
  Metadata:
    encoder         : Lavf58.26.101
    Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv444p, 512x448, q=-1--1, 60 fps, 1k tbn, 60 tbc
    Metadata:
      encoder         : Lavc58.47.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
frame=14587 fps= 60 q=-1.0 Lsize= 1625062kB time=00:04:03.13 bitrate=54753.8kbits/s speed=   1x
video:1624328kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.045149%
[libx264 @ 000001d2881a15c0] frame I:14587 Avg QP: 0.00  size:114027
[libx264 @ 000001d2881a15c0] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 000001d2881a15c0] coded y,u,v intra: 46.0% 44.6% 44.6%
[libx264 @ 000001d2881a15c0] i16 v,h,dc,p: 77% 23%  0%  0%
[libx264 @ 000001d2881a15c0] kb/s:54725.45

And here is some of the audio output (output to file):

Guessed Channel Layout for Input Stream #0.0 : mono
Input #0, dshow, from 'audio=Stereo Mix (Realtek High Definition Audio)':
  Duration: N/A, start: 11732.800000, bitrate: 705 kb/s
    Stream #0:0: Audio: pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
Press [q] to stop, [?] for help
Output #0, wav, to 'C:/users/antum/Videos/Captures/output-2019-02-13_10.52.17.456113800-audio.wav':
  Metadata:
    ISFT            : Lavf58.26.101
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, mono, s16, 705 kb/s
    Metadata:
      encoder         : Lavc58.47.100 pcm_s16le
size=       0kB time=00:00:01.01 bitrate=   0.6kbits/s speed=   2x    
size=       0kB time=00:00:01.51 bitrate=   0.4kbits/s speed= 1.5x    
size=       0kB time=00:00:02.01 bitrate=   0.3kbits/s speed=1.33x    
size=       0kB time=00:00:02.51 bitrate=   0.2kbits/s speed=1.25x    
size=     256kB time=00:00:03.01 bitrate= 696.7kbits/s speed= 1.2x    
size=     256kB time=00:00:03.51 bitrate= 597.7kbits/s speed=1.16x    
size=     256kB time=00:00:04.01 bitrate= 523.0kbits/s speed=1.14x    
size=     256kB time=00:00:04.51 bitrate= 465.1kbits/s speed=1.12x    
size=     256kB time=00:00:05.01 bitrate= 418.6kbits/s speed= 1.1x    
size=     256kB time=00:00:05.51 bitrate= 380.7kbits/s speed=1.09x    
size=     512kB time=00:00:06.01 bitrate= 697.9kbits/s speed=1.09x    
size=     512kB time=00:00:06.51 bitrate= 644.3kbits/s speed=1.08x    
size=     512kB time=00:00:07.01 bitrate= 598.3kbits/s speed=1.07x    
...
...
size=   20224kB time=00:03:55.01 bitrate= 705.0kbits/s speed=   1x    
size=   20224kB time=00:03:55.51 bitrate= 703.5kbits/s speed=   1x    
size=   20224kB time=00:03:56.01 bitrate= 702.0kbits/s speed=   1x    
size=   20224kB time=00:03:56.51 bitrate= 700.5kbits/s speed=   1x    
size=   20224kB time=00:03:57.01 bitrate= 699.0kbits/s speed=   1x    
size=   20224kB time=00:03:57.51 bitrate= 697.5kbits/s speed=   1x    
size=   20480kB time=00:03:58.01 bitrate= 704.9kbits/s speed=   1x    
size=   20480kB time=00:03:58.51 bitrate= 703.4kbits/s speed=   1x    
size=   20480kB time=00:03:59.01 bitrate= 701.9kbits/s speed=   1x    
size=   20480kB time=00:04:00.01 bitrate= 699.0kbits/s speed=   1x    
size=   20480kB time=00:04:00.51 bitrate= 697.6kbits/s speed=   1x    
size=   20736kB time=00:04:01.01 bitrate= 704.8kbits/s speed=   1x    
size=   20736kB time=00:04:01.51 bitrate= 703.4kbits/s speed=   1x    
size=   20736kB time=00:04:02.01 bitrate= 701.9kbits/s speed=   1x    
size=   20736kB time=00:04:02.51 bitrate= 700.5kbits/s speed=   1x    
  • Are you using the same ffmpeg as months ago when it worked? – llogan Feb 13 at 19:21
  • I have upgraded to a newer version to see if it would fix the problem. – AntumDeluge Feb 14 at 23:01
  • If an old version worked and the new one is worse it could indicate a regression. If you are familiar with git bisect and compiling you could find the responsible commit, but it can be time consuming and tedious. – llogan Feb 14 at 23:42

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