Если входное разрешение изменится, то ffmpeg продолжит писать картинки с исходным размером
ffmpeg -i "rtmp://example.com/live/stream" -f image2 -update 1 C:\tmp\stream.jpg
Сам он видит, что разрешение меняется, пишет
Reconfiguring filter graph because video parameters changed to yuv420p(unknown, unknown), 640x480
Reconfiguring filter graph because video parameters changed to yuv420p(unknown, unknown), 320x240
Reconfiguring filter graph because video parameters changed to yuv420p(unknown, unknown), 1280x960
но на выходе размер картинок остается первоначальным...
Metadata:
|RtmpSampleAccess: true
Duration: N/A, start: 631336.102000, bitrate: N/A
Stream #0:0: Video: h264 (Constrained Baseline), yuv420p(progressive), 320x240, 15 fps, 15 tbr, 1k tbn, start 631336.125000
Stream #0:1: Audio: aac (LC), 48000 Hz, stereo, fltp, start 631336.102000
Stream mapping:
Stream #0:0 -> #0:0 (h264 (native) -> mjpeg (native))
Press [q] to stop, [?] for help
Output #0, image2, to 'C:\tmp\stream.jpg':
Metadata:
|RtmpSampleAccess: true
encoder : Lavf62.3.100
Stream #0:0: Video: mjpeg, yuv420p(pc, progressive), 320x240, q=2-31, 200 kb/s, 1 fps, 1 tbn
Metadata:
encoder : Lavc62.11.100 mjpeg
Side data:
cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
