“I wanna DL .mkv files onto my new Kindle Fire HD. Do 720p and 1080p .mkv files work on the 8.9-inch Kindle Fire?”
The Amazon Kindle Fire HD 7/8.9 supports many file formats, but MKV is not on the list. MKV files can contain lots of different types of video and audio streams. You'd have to try it and see. If you want to save yourself the hassle of testing each one, you can use Pavtube Video Converter to convert your MKV files on your computer and then transfer them to your Kindle Fire.
About Pavtube Video Converter
This program does a great job when running as a Kindle Fire HD Video Converter, which comes with well support for 1080p/720p MKV recordings to Kindle Fire HD 7/8.9 conversion and MKV to Kindle Fire HD 7/8.9 transcoding. Conversion speed seems fine and the generated videos look good on the Kindle Fire HD 7/8.9 tablet.
Kindle Fire HD Video Converter
Guide: How to make MKV movies and 1080p/720p MKV recordings viewable on Kindle Fire HD 7/8.9?
Step 1: Launch Pavtube Kindle Fire HD Video Converter, and click “Add video” or “Add from folder” button to load 1080p/720p MKV movie files that you want to play with Kindle Fire HD 7/8.9.
Step 2: Click “Format” bar and Choose “Amazon Kindle Fire H.264 (*.mp4)” as output format for Kindle Fire HD 7/8.9 from “Android” presets list.
Step 3: Click “Settings” button to adjust video and audio parameters on “Profile Settings” panel. Then click “OK” to confirm your selection. The recommended video and audio settings for Kindle Fire HD 7/8.9 are listed as below.
Video Codec: h264
Frame Rate (fps):24
1. If you prefer to get a file with much clearer image quality and do not mind generating a relatively large file size, you can change the video bit rate higher to 1,500~2,500. In general, the higher bit rate, the bigger output file size.
2. If you would like to experience 1080p playback quality on your Kindle Fire HD 8.9, you can set the video size (pix) at 1920*1080.
3. You may also download more Kindle Fire HD presets(Windows only) or create your own preset.
Step 4: Click “Convert” button to start conversion. Pavtube Kindle Fire HD Video Converter will finish MKV/1080p/720p MKV to Kindle Fire HD 7/8.9 conversion at fast speed, especially when you enabling CUDA or AMD APP (ATI Stream) acceleration. (The Mac version does not support CUDA or AMD speedup.)
Note that CUDA/AMD is accessible only when there is an NVIDIA/AMD graphics card that supports GPU en-decoding acceleration installed on your computer. The CUDA/AMD button will be grayed out/ denied when the software fails to detect a satisfactory NVIDIA/AMD graphics card. The CUDA and AMD APP acceleration only work when creating H.264 encoded video files. See if your computer supports CUDA.