ffmpeg

问题 I need to split a webm encoded video into png frames, without losing transparency. I use the following ffmpeg command: ffmpeg -i dancer1.webm -pix_fmt rgba frames/%04d.png This produces a directory of pngs, but why is each output frame is missing transparency? I have used this example video, which contains an alpha channel. See it playing over a background here. Here's an example output frame from ffmpeg: ffmpeg produces the following output when it runs: ffmpeg version N-60294-g549f052

问题 My problem is that i need to extract with FFMPEG the audio contained in a video with the same duration. But for some files that i tested, the audio's duration is sometimes shorter than the video's duration. I need to have the exact same duration between the audio and the video file. The command that i have already tried is this following: ffmpeg -i input_video.mp4 output_audio.wav How can i fix this with options in my command ? 回答1: I found the solution. To get an audio extract with the exact

问题 I'm attempting to run the following command in PHP (on Ubuntu): <?php if (exec("/home/johnboy/ffmpeg/ffmpeg -i test1.mp4 -acodec aac -ab 128kb -vcodec mpeg4 -b 1220kb -mbd 1 -s 320x180 final_video.mov")) { echo "Success"; } else { echo "No good"; } And I always get "No good" echoed back, and no file created. Interestingly, if I run the same exact command in Shell, it works, no problems. Also, when I run the same code above, but subsitute "whoami" instead of the ffmpeg stuff, it works. (It

问题 I'm attempting to run the following command in PHP (on Ubuntu): <?php if (exec("/home/johnboy/ffmpeg/ffmpeg -i test1.mp4 -acodec aac -ab 128kb -vcodec mpeg4 -b 1220kb -mbd 1 -s 320x180 final_video.mov")) { echo "Success"; } else { echo "No good"; } And I always get "No good" echoed back, and no file created. Interestingly, if I run the same exact command in Shell, it works, no problems. Also, when I run the same code above, but subsitute "whoami" instead of the ffmpeg stuff, it works. (It

问题 I'm attempting to run the following command in PHP (on Ubuntu): <?php if (exec("/home/johnboy/ffmpeg/ffmpeg -i test1.mp4 -acodec aac -ab 128kb -vcodec mpeg4 -b 1220kb -mbd 1 -s 320x180 final_video.mov")) { echo "Success"; } else { echo "No good"; } And I always get "No good" echoed back, and no file created. Interestingly, if I run the same exact command in Shell, it works, no problems. Also, when I run the same code above, but subsitute "whoami" instead of the ffmpeg stuff, it works. (It

问题 I'm attempting to run the following command in PHP (on Ubuntu): <?php if (exec("/home/johnboy/ffmpeg/ffmpeg -i test1.mp4 -acodec aac -ab 128kb -vcodec mpeg4 -b 1220kb -mbd 1 -s 320x180 final_video.mov")) { echo "Success"; } else { echo "No good"; } And I always get "No good" echoed back, and no file created. Interestingly, if I run the same exact command in Shell, it works, no problems. Also, when I run the same code above, but subsitute "whoami" instead of the ffmpeg stuff, it works. (It

问题 I want to record live webcam video on mac OS using ffmpeg in any format. I tried a lot but not able to find out command for recoding of video. So Please any one can tell me ffmpeg command for capture video using web cam for mac os. Thanx in advance. 回答1: for mac os try: ffmpeg -f avfoundation -i "0" -f mpeg1video -b:v 800k -r 30 回答2: FFmpeg can't record using the iSight camera. But, this dude shows how to record a time lapse video on Mac using the cmd-line. 来源： https://stackoverflow.com

问题 I want to record live webcam video on mac OS using ffmpeg in any format. I tried a lot but not able to find out command for recoding of video. So Please any one can tell me ffmpeg command for capture video using web cam for mac os. Thanx in advance. 回答1: for mac os try: ffmpeg -f avfoundation -i "0" -f mpeg1video -b:v 800k -r 30 回答2: FFmpeg can't record using the iSight camera. But, this dude shows how to record a time lapse video on Mac using the cmd-line. 来源： https://stackoverflow.com

问题 I want to concatinate 4 different videos of 4 different resolution and type into 1 video which can be played in android. I am using ffmpeg ported on android using https://github.com/guardianproject/android-ffmpeg So I have these 4 different types of videos 1) ./ffmpeg -i 1.mp4 Video: h264 (High), yuv420p, 1920x1080, 16959 kb/s, 29.85 fps, 90k tbr, 90k tbn, 180k tbc Audio: aac, 48000 Hz, stereo, s16, 106 kb/s 2) ffmpeg -i 2.mp4 Video: h264 (Constrained Baseline), yuv420p, 640x480, 3102 kb/s,

问题 Given the fact that public file paths will generally not be available in Android Q with scoped storage, I am attempting to figure out how to make my FFmpeg audio decoder work with file descriptors, without copying the file to my app's private directories. We can easily get a file descriptor using the methods described in Android Q privacy changes, and it is possible to open the file descriptor using the pipe protocol as described in Passing a native fd int to FFMPEG from openable URI. However