Low conversion quality using ffmpeg I need to convert flv video into mp4 video, so I used this command:

ffmpeg -i input.flv -c -vcodec libx264 -acodec copy output.mp4


But output video has little bit worse video quality, how can I fix it?

MP4 info (output):


video: 472kb/s bitrate, 680*480, 24 FPS
audio: 112kb/s bitrate, 44.1 kHz, mpeg audio, stereo


FLV info (input):


video: 1500kb/s bitrate, 680*480, 24 FPS
audio: 112kb/s bitrate, 44.1 kHz, mpeg audio, stereo


UPDATE:

I tried with -crf 18 and this is result (colors of output are more bright and look at that yellow line on the cap, on the output image that yellow line contains  something like noise).

Input:



Output:
Lossy codecs such as x264 degrade the image quality by design, if you don't want to lose image quality you either have to use a lossless codec or better yet, not re-encode at all.

I assume the source material is either H.264 or MPEG-2, so the best solution in your case would be to simply copy all the streams into the new container:

ffmpeg -i input.flv -c copy output.mp4


Here's the command for using x264's lossless mode if you have to re-encode for whatever reason:

ffmpeg -i input.flv -c:a copy -c:v libx264 -crf 0 output.mp4