How to splice sections of a video with avconv

avconvffmpegvideo editing

I have figured out so far that you can cut a section from a video with avconv with a command like this (cuts from 1:00-3:00):

avconv -ss 00:01:00 -i "input.avi" -t 00:02:00 -c:v libx264 -crf 23 "output.mp4"

But how would I cut two (or more) sections from the video and combine them into one video? For example, taking 1:00-3:00 as above, plus 8:00-10:00, making a final 4 minute video.

I guess I can do them separately then concatenate them, but is there a simpler way?

Best Answer

I believe you will have to cut separate chunks, then concatenate them. Don't use cat for that, as timecodes will be all over the place.

If the video chunks are mp4, use mp4box (from the gpac package) for concatenation:

mp4box -cat vid1.mp4 -cat vid2.mp4 ... -cat vidN.mp4 -new vid1-N.mp4

Related Solutions

Downsampling a video with avconv / ffmpeg

The final line in the output log is too generic — you'll have to look up further. The error is this:

[ac3 @ 0x9fdc740] invalid bit rate

The problem is that for some reason avconv wants to encode your MP3 audio to AC3. In fact, when you're only resizing video, you can leave the audio bitstream alone.

Note that resizing and re-encoding will lower your quality drastically. So, unless you really need to, don't do it. Your video will suffer from generation loss.

If you can, avoid using MPEG-4 Part 2 codecs (Xvid, or the libavcodec-native mpeg4), and use MPEG-4 Part 10 / H.264 codecs instead (e.g., x264). Since H.264 isn't properly supported in AVI containers, we'll use MP4 instead, which should be your container of choice instead of AVI most of the time.

ffmpeg -i in.avi -c:a copy -c:v libx264 -crf 23 -s:v 640x360 output.mp4

This will copy the audio stream (-c:a copy), encode the video to x264 (-c:v libx264) with a constant quality of 23 (-crf). Use a lower value here for better quality (with sane values from 18–28). The size will be changed with -s:v.

I'm using FFmpeg synonymously with Libav here, since the syntax should be the same. I would however recommend you to ditch the default Libav version that ships with Ubuntu and compile FFmpeg from source or use a recent Linux static build.

Trim and fade in/out video and audio with avconv (or different tool)

I finally found the time to try the answer suggested by @Mario G., but it seemed extremely cumbersome. I need to do this many dozens of times. I read the documentation of ffmpeg and found it much more powerful than avconv, including fading for audio and video, so the solution is

ffmpeg -i input.mts -map 0:0 -map 0:3 -ss 0:0:07 -to 0:59:57.5 -vf 'fade=t=in:st=7:d=2,fade=t=out:st=3595.5:d=2,crop=out_h=692' -af 'afade=t=in:st=7:d=2,afade=t=out:st=3595.5:d=2' out.mov

So the st= and d= parameters for the fade take times in seconds, no need for converting to frames.

I also discovered the -to option to take the end time directly instead of calculating the length.

This command does all steps

channel selection with -map,
trimming with -ss and -to,
video fading with -vf option fade=t=in and fade=t=out,
audio fading with -af option afade=t=in and afade=t=out and
cropping with -vf option crop=

in a single step.

Best Answer

Related Solutions

Downsampling a video with avconv / ffmpeg

Trim and fade in/out video and audio with avconv (or different tool)

Related Question