Question:

I´m already working on project with 3d video an i have problem,i got left and right channel of video a a ineed to merge it into side by side.I already read some blogs about this problem and i got this code:

ffmpeg -i avatar35l.avi -vf "movie=avatar35r.avi [in1]; [in]pad=1920*2:1080[in0]; [in0][in1] overlay=1920:0 [out]" avatar35sbs.avi

it works,but i got significant quality loss and i need a quality of output video same as input video,30fps,1080p,same lenght,i´m a new one to ffmpeg and i need a concrete example of that

Can anybody help me?

You'll have to use a truly lossless format if you require "a quality of output video same as input video". Example for ffv1 using the <a href="https://ffmpeg.org/ffmpeg-filters.html#hstack" rel="nofollow">hstack</a> filter instead of movie+pad+overlay:

ffmpeg -i left.avi -i right.avi -filter_complex hstack -c:v ffv1 output.avi

FFmpeg supports several additional lossless compressed formats such as:

<ul><li>lossless H.264: -c:v libx264 -crf 0</li> <li>huffyuv: -c:v huffyuv</li> <li>ffvhuff: -c:v huffyuv</li> <li>UT Video: -c:v utvideo</li> <li>And of course lossless uncompressed formats including rawvideo.</li> </ul>

Since it is lossless the output file will be huge, and your player or device will probably not like it.

Of course what you may actually want is "lossy, yet 'visually lossless', but not a gigantic, huge file like true lossless provides". In that case use:

ffmpeg -i left.avi -i right.avi -filter_complex "hstack,format=yuv420p" -c:v libx264 -crf 18 output.mp4

You didn't mention audio. If you want to merge the audio from each input as well use the <a href="https://ffmpeg.org/ffmpeg-filters.html#amerge" rel="nofollow">amerge</a> filter:

ffmpeg -i left.avi -i right.avi -filter_complex "[0:v][1:v]hstack,format=yuv420p[v];[0:a][1:a]amerge[a]" -map "[v]" -map "[a]" -c:v libx264 -crf 18 -ac 2 output.mp4

See <a href="https://trac.ffmpeg.org/wiki/Encode/H.264" rel="nofollow">FFmpeg Wiki: H.264 Video Encoding</a>.