How to Rip DVD ISO to MKV File?

"My friends gave me some DVD ISO files. I need to convert them into MKVs. What kind of software can do the work? I have tried common video converter which can be not support to input ISO files. So, I guess I need another sort of tools. Please give me some advices. Thanks in advance. "
I will recommend you Blu ray to MKV converter, which can be not only capable of rip DVD ISO to MKV lossless, but also reserve the multiple subtitles and audio tracks meanwhile. Now let's learn more about how to rip DVD ISO to MKV without quality loss.
Step1. Load DVD ISO files to Blu ray to MKV Converter
Launch Blu ray to MKV Converter software, click "DVD/Blu ray disc" button to load DVD ISO image file into the program. (Just before loading, you need use vitual BD drive to read the DVD ISO file first).

Step2. Choose the titles and chapters you want to rip to MKV
After loaded the DVD ISO file for the program, there will be a list showing below. If you want to rip all the DVD titles or chapters to MKV, you then can click the "Check All" button to select all titles. Or you can click "Uncheck All" button to cancel your former selection.
Step3. Edit
Click "Edit" button to edit the imported files. To do lossless DVD to MKV conversion, you can choose "Lossless" in format and keep the audio tracks and subtitle streams you like to conserve.
Step4. Rip DVD ISO to MKV
Then revisit the home interface and click "Convert MKV" to start to rip DVD ISO to MKV. After the conversion is finished, click "Open" button to get the ripped MKV files.