I have a video that potplayer plays smoothly w/o sweating. When I try to process the video with ffmpeg, I get the following error:
ffmpeg -i input.mkv -f image2 frame-%06d.png
Input #0, png_pipe, from 'input.mkv':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: png, rgba(pc, gbr/bt709/iec61966-2-1), 1x1 [SAR 4724:4724 DAR 1:1], 25 fps, 25 tbr, 25 tbn
Stream mapping:
Stream #0:0 -> #0:0 (png (native) -> png (native))
Press [q] to stop, [?] for help
[png @ 0000023c7f794723] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f796345] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f799def] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f79eaff] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a1530] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a420f] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a714e] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a7578] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a8000] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a78c0] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a83c0] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[png @ 0000023c7f7a7c80] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
Output #0, image2, to 'frame-%06d.png':
Metadata:
encoder : Lavf61.7.100
Stream #0:0: Video: png, rgba(pc, gbr/bt709/iec61966-2-1, progressive), 1x1 [SAR 4724:4724 DAR 1:1], q=2-31, 200 kb/s, 25 fps, 25 tbn
Metadata:
encoder : Lavc61.19.101 png
[png @ 0000023c7f783500] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[vist#0:0/png @ 0000023c7f779fc0] [decng @ 0000023c7f781280] Error submitting packet to decoder: Invalid data found when processing input
Last message repeated 1 times
[png @ 0000023c7f794380] Invalid PNG signature 0xFFFFFFFFFFFFFFFF.
[vist#0:0/png @ 0000023c7f779fc0] [decng @ 0000023c7f781280] Error submitting packet to decoder: Invalid data found when processing input......

Is there a way to direct Plotplayer to output the videofile it is playing?

Also, is there a way to re-encode without scaling or anything with FFMPEG?

Here is what Potplayer displays as video info:
Filename: Input.mkv
Local Time: 19:56:58, Playback Time: 00:00:09/01:06:35(0.3%), Elapsed/Total Frames: 299/119742
Preset: *Default preset, CPU: 1/3%, GPU: 1.4%, VRAM: 131.5/610.4MB
PotPlayer/OS Version: 250313(1.7.22508), Windows 11 24H2(10.0.26100)
Video Codec: Built-in FFmpeg Decoder(h264, Thread Frame)
Input: H264(24 bits), 1920×1080(1.78:1/1.78:1), FPS: 29.97, Bitrate: 728.2 kbps
Transform: 1080p, Format: yuv420p, Location: left
Output: NV12(12 bits), 1920×1080(1.78:1/1.78:1), FPS: 29.97(28.543)->3.15
Renderer: Enhanced Video Renderer(Custom Present)
- Formats: NV12(Input)->XRGB(Video->BackBuffer->Display)
Resizer: Disabled, Presentation: D3D 9Ex Discard, Render Device: AMD Radeon(TM) Graphics
Frames: 943, Dropped: 1, Jitter: 250ms, Sync Offset: 0/0ms, Queue: 5, Refresh Rate: 32Hz
Frame Size: 1920×1080(1.78:1) - 1920×1080(1.78:1) = 0×0(0×0%)
Audio Codec: Built-in FFmpeg Decoder(aac)
Input: AAC ADTS(0x4441), 48000 Hz, 2 Channels, 0-bit, 4.87(131.1) kbps
Output: PCM(0x1), 48000 Hz, 2 Channels, 16-bit, 1536 kbps
Rendering: PCM(0x1), 48000 Hz, 2 Channels, 16-bit, 1536 kbps
Renderer: DirectSound Audio Renderer