How to get better quality converting MP4 to WMV with ffmpeg?

问题

I am converting MP4 files to WMV with these two rescaling commands:

ffmpeg -i test.mp4 -y -vf scale=-1:360 test1.wmv
ffmpeg -i test.mp4 -y -vf scale=-1:720 test2.wmv

I've also tried:

ffmpeg -g 1 -b 16000k -i test1.mp4 test1.wmv

However, the .wmv files that are produced are "blocky and grainy" as you can see here in a small section of a video screenshot:

These are the sizes:

test.mp4 - 106 MB
test1.wmv - 6 MB
test2.wmv - 16 MB

How can I increase the quality/size of the resulting .wmv files (the size of the .wmv files is of no concern)?

回答1:

Consider the following command instead (some outdated commands in the final answer section):

ffmpeg -i test.mp4 -c:v wmv2 -b:v 1024k -c:a wmav2 -b:a 192k test1.wmv

REFERENCES

• List item https://askubuntu.com/questions/352920/fastest-way-to-convert-videos-batch-or-single

回答2:

You can simply use the -sameq parameter ("use same quantizer as source") which produces a much larger sized video file (227 MB) but with excellent quality.

ffmpeg -sameq -i test.mp4 -y -vf scale=-1:360 test1.wmv

In newer versions of ffmpeg flag '-sameq' has been removed. To achieve similar results one should use 'qscale' flag with 0 value:

ffmpeg -sameq -i test.mp4 -qscale 0 -vf scale=-1:360 test1.wmv

回答3:

One thing I discovered after many frustrating attempts of enhancing the final quality was that if you don't specify a bitrate, it'll use a quite low average. Try -b 1000k for a starting point, and experiment increasing or decreasing it until you reach the desired result. Your file will be quite bigger or smaller, accordingly.

来源：https://stackoverflow.com/questions/11079577/how-to-get-better-quality-converting-mp4-to-wmv-with-ffmpeg