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  1. About a year ago I was desperately looking for a mkv to mp4 conversion system that would keep subtitles in their intended positions without making them look particularily terrible, and eventually just settled for the subtitles FormatFactory provides. Today I discovered mediacoder and it basically does exactly what I need to.

    However, I do notice some definite quality loss upon conversion, which is totally expected. But what I also notice is that when I use the "copy video" option that the quality is significantly better (again, expected)

    The only problem that arises is that I can not seem to find a way to keep the subtitles as well as the quality copying the video provides. Is there any way to do this with this program? Or maybe just an entirely new program that does this better?

    Sorry for possible grammatical errors or typos...low on sleep, heh
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  2. I'm a MEGA Super Moderator Baldrick's Avatar
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    I guess you are hardcoding the subtitle into the video? Then can't you use copy video and must reconvert.

    Try increase the bitrate to get a bit better quality. Or adjust the quantizer/quality value (lower for x264 video for example).
    Last edited by Baldrick; 29th Jan 2014 at 08:31.
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  3. No matter how high I set the bitrate there always seems to be a significant drop in quality compared to the original file...I didn't expect it to be totally perfect, but I didn't expect it at all to be THIS bad. It's particularily noticable during high movement scenes.

    I also see literally no difference between whatever the percentages seem to indicate under video quality when I set the rate mode to variable bitrate.

    Dunno if anyone else here is very familiar with this program, but any help to make the video as high quality as I can would be appreciated.


    EDIT: Not sure what I did, but I got near perfect quality...on the downside, this file is roughly 9x the size of the original. I'm not sure exactly how this happens, heh

    EDIT 2: I found a system that definitely works. Out of courtesy I will leave what I did here to hopefully inform those with pleb knowledge such as myself who face this problem in the future. For some reason using the GPU to encode the files only set things to come out a certain quality--no matter what percentage I set it to. Putting the encoder on auto, and setting the percentage to 60, I have removed the vast majority of the artifacts while still keeping the file size ~100MB smaller than the source.
    Last edited by Acrylik; 30th Jan 2014 at 03:27.
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  4. I'm a MEGA Super Moderator Baldrick's Avatar
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    Yep. Hardware GPU encoding is often very crappy.
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  5. ffmpeg + mp4box can repake mkv to mp4 container with subtitles.

    first get the trackID of the subtitles you want.

    ffmpeg -i in.mkv

    if the trackID is 0:2 export the subtitles track by this command

    ffmpeg -i in.mkv -map 0:2 out.srt

    convert the .srt in subrip format to ttxt using mp4box

    mp4box -ttxt out.srt

    put the ttxt file into mp4. language code can be found by mp4box -languages

    mp4box -add out.ttxt:lang=eng subtitles.m4v

    if the video and audio trackid is 0:0 and 0:1

    ffmpeg -i in.mkv -i subtitles.m4v -map 0:0 -map 0:1 -map 1:0 -c copy out.m4v

    if you want to conver the ac3 audio to aac format, which is supported by iOS, you can use this

    ffmpeg -i in.mkv -i subtitles.m4v -map 0:0 -map 0:1 -map 1:0 -acodec libvo_aacenc -ac 2 (specifies audio channels) -vcodec copy - scodec copy out.m4v

    the end. and it is very fast. You can turn m4v into mp4 if you like.
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