billw2
commented
5 years ago On Wed, 31 Jul 2019 14:17:54 -0700 AntonJouri notifications@github.com wrote:
When recording video with audio, the mic is ahead of the video, and it is getting worse every minute. It is known, that the fps of Raspi-Camera and USB-Microphones usually don’t match. So I wonder, how do you compensate the drift?
I tried to compensate by setting the mp4box-fps just by 1 higher than fps, e.g. fps=23, mp4box=24, what tuned out as video is ahead of the mic-audio. I tried comma-values in the config-file directly, like fps=23.4 (period) or 23,3 (comma), and mp4box=23,8 or 23.9, and many other pairs of values, but as long as only integer values are processed, I can not find a matching value to compensate the drift.
Or, is there any parameter to adjust for the process that converts h246 and audio to mp4 to minimize the drift?
I´m using Raspberry Pi3+ with BusterLite as basis for PiKrellCam. May be I should downgrade?
Right now I´m out of ideas. Any hint appreciated.
Greetings, Gunneg
The config takes only integer values so there is no way to do any compensation now. I could change the type to float so factional values could be entered, but your asking this has made me think that a better way would be for pikrellcam to calculate a fps needed to make video time match audio time and use that in the mp4box. I'm wondering about the magnitude of the drift you get, so could you look in the pikrellcam log and tell me some rate results you get for 2 or 3 typical video records? Sound like you have long videos, but for a short video I get this for a "Motion record stop" line in the log:
Motion record stop (size:5.0MB < /tmp:257.5MB) vid_time:10.04 vid_fps:24.00 audio_frames:481965 audio_rate: 48000
If I could see some log numbers like that for some of your videos it would help and in the meantime I'll think about making the changes to pikrellcam of fractional fps config and automatic calculating a mp4box fps.
Thanks, Bill
-- Bill Wilson billw@gkrellm.net
AntonJouri
n1c085
When recording video with audio, the mic is ahead of the video, and it is getting worse every minute. It is known, that the fps of Raspi-Camera and USB-Microphones usually don’t match. So I wonder, how do you compensate the drift?
I tried to compensate by setting the mp4box-fps just by 1 higher than fps, e.g. fps=23, mp4box=24, what tuned out as video is ahead of the mic-audio. I tried comma-values in the config-file directly, like fps=23.4 (period) or 23,3 (comma), and mp4box=23,8 or 23.9, and many other pairs of values, but as long as only integer values are processed, I can not find a matching value to compensate the drift.
Or, is there any parameter to adjust for the process that converts h246 and audio to mp4 to minimize the drift?
I´m using Raspberry Pi3+ with BusterLite as basis for PiKrellCam. May be I should downgrade?
Right now I´m out of ideas. Any hint appreciated.
Greetings, Gunneg