ffmpeg av_seek_frame with AVSEEK_FLAG_ANY causes grey screen
ffmpeg, media-player, seek
Solution
Actually, `AVSEEK_FLAG_BACKWARD` indicates that you want to find closest keyframe having a smaller timestamp than the one you are seeking.
By using `AVSEEK_FLAG_ANY`, you get the frame that corresponds exactly to the timestamp you asked for. But this frame might not be a keyframe, which means that it cannot be fully decoded. That explains your "grey screen", that appears until the next keyframe is reached.
The solution would therefore be to seek backward using `AVSEEK_FLAG_BACKWARD` and, from this keyframe, read the next frames (e.g. using `av_read_frame()`) until you get to the one corresponding to your timestamp. At this point, your frame would be fully decoded, and would not appear as a "grey screen" anymore.
NOTE: It appears that, for some reason, `av_seek_frame()` using `AVSEEK_FLAG_BACKWARD` returns the next keyframe when the frame that I am seeking is the one directly before this keyframe. Otherwise it returns the previous keyframe (which is what I want). My solution is to change the timestamp I give to `av_seek_frame()` to ensure that it will return the keyframe before the frame I am seeking.
Problem
Problem: omxplayer's source code calls the ffmpeg `av_seek_frame()` method using the `AVSEEK_FLAG_BACKWARD` flag. Although not 100% sure, I believe this seeks to the closest i-frame. Instead, I want to seek to exact locations, so I modified the source code such that the `av_seek_frame()` method now uses the `AVSEEK_FLAG_ANY` flag. Now, when the movie loads, I get a grey screen, generally for 1 second, during which I can hear the audio. I have tried this on multiple computers (I am actually synchronizing them, therefore, at the same time too) so it is not a n isolated incident. My guess is that seeking to non i-frames is computationally more expensive, resulting in the initial grey screen. Question: How, using ffmpeg, can I instruct the audio to wait until the video is ready before proceeding.