[FFmpeg-user] Frame rate and movies from images
jpalmer at worldnow.com
Mon Jul 22 20:12:58 CEST 2013
Thanks for your reply.
If I attempt to use -r as an input option, ffmpeg gives me the error: Could not set video options: Input/output error.
I think this is because my input is not a series of image sequences nor is it a video file. It is real time streaming from an AJA Capture Source. As such, I am unable to set the frame rate of the input.
Any other ideas are welcome and appreciated. Thanks.
From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of thljcl
Sent: Sunday, July 21, 2013 7:31 PM
To: ffmpeg-user at ffmpeg.org
Subject: Re: [FFmpeg-user] Frame rate and movies from images
You made an error for not recognizing the difference between -r as an input option or output option. If your source is a series of image sequence, ffmpeg will assume the frame rate of 25 FPS if none is specified as the input option; if your source is a video file, the frame rate of the source will be regarded as input option if none is specified. Just type -r "6"
before -i should serve your purpose, if I understand you correctly. -r before -i will force the frame rate on the source while ignoring the frame rate of the source, which will result in slowing down or speeding up of the playback of the video. -r after -i is the frame rate for output video, which if the frame rate is high enough, will preserve the playback speed or the length by adding or dropping frames. If the source is of variable frame rate, specifying a different frame rate as the output option may cause the output video out of sync with audio, mainly due to changing frame rate of the source itself; even though the input video is perfectly in sync with audio. Encoding a video into a series of image sequences and specifying a frame rate as an output option can force the frame rate to be constant while preserving the original length.
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