ffmpeg have unmet dependencies (Ubuntu20) [closed]

when installing ffmpeg with ubuntu20(fosal), it have conflict dependencies:

# sudo apt-get install ffmpegReading package lists... DoneBuilding dependency tree       Reading state information... DoneSome packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: ffmpeg : Depends: libavdevice58 (= 7:4.2.7-0ubuntu0.1) but it is not going to be installed          Depends: libavfilter7 (= 7:4.2.7-0ubuntu0.1)          Depends: libavformat58 (= 7:4.2.7-0ubuntu0.1) but it is not going to be installedE: Unable to correct problems, you have held broken packages.

I solved it by install the reason of conflit library with a specific version, may be someone will need the solution.

step 1. fix-broken

sudo apt --fix-broken installReading package lists... DoneBuilding dependency tree       Reading state information... Done

step2. find the reason of unmet dependencies:

# sudo apt install libavdevice58=7:4.2.7-0ubuntu0.1 libavfilter7=7:4.2.7-0ubuntu0.1 libavformat58=7:4.2.7-0ubuntu0.1Reading package lists... DoneBuilding dependency tree       Reading state information... DoneSome packages could not be installed. This may mean that you haverequested an impossible situation or if you are using the unstabledistribution that some required packages have not yet been createdor been moved out of Incoming.The following information may help to resolve the situation:The following packages have unmet dependencies: libavformat58 : Depends: libchromaprint1 (>= 1.3.2) but it is not going to be installedE: Unable to correct problems, you have held broken packages.

Here the problem is from libchromaprint1

step3. find candidate versions of libchromaprint1(conflict reason)

# apt-cache policy libchromaprint1libchromaprint1:  Installed: (none)  Candidate: 1.5.1-1~20.04.sav0  Version table:     1.5.1-1~20.04.sav0 500        500 http://ppa.launchpad.net/savoury1/multimedia/ubuntu focal/main amd64 Packages     1.4.3-3build1 500        500 http://mirrors.cloud.aliyuncs.com/ubuntu focal/universe amd64 Packages        500 http://archive.ubuntu.com/ubuntu focal/universe amd64 Packages

step4. install the old version of libchromaprint1 to solve the conflicts

# sudo apt install libchromaprint1=1.4.3-3build1Reading package lists... DoneBuilding dependency tree       Reading state information... DoneThe following NEW packages will be installed:  libchromaprint10 upgraded, 1 newly installed, 0 to remove and 223 not upgraded.Need to get 37.6 kB of archives.

step5. reinstall ffmpeg

# sudo apt install ffmpegReading package lists... DoneBuilding dependency tree       Reading state information... Done

Done. the reason of conflict is that the latest version of libraries have conflict, by install old version of the conflicted ones to solve it.