ffmpeg

问题 I would like with ffmpeg to slow down a movie I am creating using the flag: -filter:v "setpts=2.0*PTS" However the height of my still images is not divisible by 2, so to avoid the error: height not divisible by 2 (1238x833) , I am using the flag: -vf scale="trunc(iw/2)*2:trunc(ih/2)*2" (I also tried -vf scale=1238:-2 ). When I do this the film is generated but it isn't slowed down, like if the -filter:v "setpts=2.0*PTS" wasn't there. Is there something particular to do in order to have both

问题 I would like with ffmpeg to slow down a movie I am creating using the flag: -filter:v "setpts=2.0*PTS" However the height of my still images is not divisible by 2, so to avoid the error: height not divisible by 2 (1238x833) , I am using the flag: -vf scale="trunc(iw/2)*2:trunc(ih/2)*2" (I also tried -vf scale=1238:-2 ). When I do this the film is generated but it isn't slowed down, like if the -filter:v "setpts=2.0*PTS" wasn't there. Is there something particular to do in order to have both

问题 I am trying to convert few .wav files to .mp3 format The desired .mp3 format is : I tried with FFmpeg with this code : ffmpeg -i input.wav -vn -ac 2 -b:a 160k output1.mp3 This is the output of this command on one .wav format I am getting the result but two things are different Overall bit rate mode and Writing library Writing library: LAME3.99.5 vs LAME3.100 ( I think this shouldn't make any problem?) bit rate mode Constant Vs variable How to change bit rate mode from variable to Constant?

问题 I am trying to convert few .wav files to .mp3 format The desired .mp3 format is : I tried with FFmpeg with this code : ffmpeg -i input.wav -vn -ac 2 -b:a 160k output1.mp3 This is the output of this command on one .wav format I am getting the result but two things are different Overall bit rate mode and Writing library Writing library: LAME3.99.5 vs LAME3.100 ( I think this shouldn't make any problem?) bit rate mode Constant Vs variable How to change bit rate mode from variable to Constant?

问题 I need to convert an mp4 (or any other video format) to mp3 or wav file. I am using C# Xamarin.Forms. Any library I used either doesn't work for me, or isn't compatible with android. I have tried using Xamarin.Android.FFMpeg and Xobe.FFMpeg. I repost this because it was marked as duplicate and I clearly stated that that solution isn't working for me. This is the post that was flagged as duplicate: How can I extract the audio out of a video file? (android) . Please, I tried it but it just

问题 I want to add audio to my ffmpeg cli bellow ffmpeg -framerate 25 -video_size 1920x1080 -f x11grab -i :0.0 -vf format=yuv420p http://localhost:8080/feed.ffm I tried -acodec libmp3lame, -c:a libmp3lame but it does not seam to work 回答1: You have to provide an audio input. Assuming ALSA: ffmpeg -framerate 25 -video_size 1920x1080 -f x11grab -i :0.0 -f alsa -sample_rate 48000 -channels 2 -i hw:0 -c:v libx264 -c:a aac -vf format=yuv420p http://localhost:8080/feed.ffm See FFmpeg ALSA input

问题 I want to add audio to my ffmpeg cli bellow ffmpeg -framerate 25 -video_size 1920x1080 -f x11grab -i :0.0 -vf format=yuv420p http://localhost:8080/feed.ffm I tried -acodec libmp3lame, -c:a libmp3lame but it does not seam to work 回答1: You have to provide an audio input. Assuming ALSA: ffmpeg -framerate 25 -video_size 1920x1080 -f x11grab -i :0.0 -f alsa -sample_rate 48000 -channels 2 -i hw:0 -c:v libx264 -c:a aac -vf format=yuv420p http://localhost:8080/feed.ffm See FFmpeg ALSA input

问题 I want to covert a AAC to MP3 and give metadata of comment to the MP3 file using ffmpeg. But -metadata comment doesn't work and ffmpeg doesn't return any error. My code is ffmpeg -i "test.aac" -ab 128k -metadata comment='this is test' "test.mp3" I tried -metadata description='this is test' and also update ffmpeg. Other function such as -metadata artist and -metadata album works well. What's wrong with this code? Output Stream mapping: Stream #0:0 -> #0:0 (aac (native) -> mp3 (libmp3lame))

问题 execFFmpegBinary(new String[]{"-y", "-i", path, "-s", "160x120", "-r", "25", "-vcodec", "mpeg4", "-b:v", "150k", "-b:a", "48000", "-ac", "2", "-ar", "22050", filePath}); video auto rotate after compress.. is there any solution? here is lib Link 回答1: it might be the autorotate issue in FFMPEG and you have to disable autorotate: ffmpeg -noautorotate -i input.mp4 output.mp4 if this solution doesn't solve your problem, you can get the input video rotation with Android APIs like this:

问题 execFFmpegBinary(new String[]{"-y", "-i", path, "-s", "160x120", "-r", "25", "-vcodec", "mpeg4", "-b:v", "150k", "-b:a", "48000", "-ac", "2", "-ar", "22050", filePath}); video auto rotate after compress.. is there any solution? here is lib Link 回答1: it might be the autorotate issue in FFMPEG and you have to disable autorotate: ffmpeg -noautorotate -i input.mp4 output.mp4 if this solution doesn't solve your problem, you can get the input video rotation with Android APIs like this: