How to convert mkv movies to mp4 for streaming to XBox 360

Question

I recently purchased a Synology Diskstation DS412+, and I have a number of .mkv movies which I would like to convert/transcode to mp4 files, so that I can stream them directly to my XBox 360. I use Handbrake on my laptop, but I would rather have this happen directly on my NAS.

I'm very rusty on Linux and new to transcoding, but the script I currently have is the following:

#!/bin/bash
for dir in *; do
  if test -d "$dir"; then
    #echo $dir
    for file in "$dir"/*.mkv; do
      noextension=${file%.*}.mp4
      ffmpeg -y -i "$file" -vcodec copy -acodec copy "$noextension"
    done
  fi
done

Which, as I understand it, simply copies the audio and video components within the mkv container, and inserts them into a new mp4 container. This has worked for several of my files, but there are a number for which this does not work.

The following is an example of the output for a failed run:

ffmpeg version UNKNOWN, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep 16 2013 00:45:02 with gcc 4.2.1
  configuration: --prefix=/usr/syno --arch=i686 --target-os=linux --cross-prefix=/usr/local/i686-linux-gnu/bin/i686-linux-gnu- --enable-cross-compile --enable-optimizations --disable-yasm --disable-altivec --enable-pic --enable-shared --disable-static --disable-swscale-alpha --disable-ffserver --disable-ffplay --enable-libmp3lame --enable-libfaac --enable-nonfree --enable-version3 --enable-libopencore-amrnb --enable-libopencore-amrwb --disable-decoder=amrnb --disable-indev=alsa --disable-outdev=alsa --disable-encoder=dca --disable-encoder=ac3 --disable-encoder=ac3_fixed --disable-encoder=ac3_float --disable-encoder=eac3 --disable-decoder=dca --disable-decoder=eac3 --disable-decoder=truehd --cc=/usr/local/i686-linux-gnu/bin/i686-linux-gnu-ccache-gcc
  libavutil    50. 40. 1 / 50. 40. 1
  libavcodec   52.120. 0 / 52.120. 0
  libavformat  52.108. 0 / 52.108. 0
  libavdevice  52.  4. 0 / 52.  4. 0
  libavfilter   1. 77. 0 /  1. 77. 0
  libswscale    0. 14. 0 /  0. 14. 0
[matroska,webm @ 0x80726c0] Estimating duration from bitrate, this may be inaccurate

Seems stream 1 codec frame rate differs from container frame rate: 47.95 (5994/125) -> 23.98 (24000/1001)

...and then a list of input chapter start and end times and then...

 Stream #0.0(eng): Audio: aac, 48000 Hz, stereo, s16 (default)
 Stream #0.1(eng): Video: h264 (High), yuv420p, 1280x692 [PAR 1:1 DAR 320:173], 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)

...and then a list of output chapter start and end times and then...

Stream #0.0(eng): Video: ![0][0][0] / 0x0021, yuv420p, 1280x692 [PAR 1:1 DAR 320:173], q=2-31, 2997 tbn, 23.98 tbc (default)
Stream #0.1(eng): Audio: libfaac, 48000 Hz, stereo (default)
Stream mapping:
  Stream #0.1 -> #0.0
  Stream #0.0 -> #0.1
Press [q] to stop encoding
[mp4 @ 0x808a020] pts < dts in stream 0
av_interleaved_write_frame(): Invalid data found when processing input

The XBox support website gives details on supported file types, with mp4 included in the H.264 standard: http://support.xbox.com/ar-SA/xbox-360/system/audio-video-playback

I'm at a bit of a loss. I've read through http://www.ffmpeg.org/ffmpeg.html but the error message from ffmpeg doesn't seem very helpful, and resources are sparse at best when it comes to running this stuff on a Synology Box.

I have tried a few permutations of my script, such as:

ffmpeg -i "$file" "$noextension"

and

ffmpeg -y -i "$file" -vcodec mpeg4 -acodec libfaac "$noextension"

But those both give me the following error:

Error while opening encoder for output stream #0.0 - maybe incorrect parameters such as bit_rate, rate, width or height

I assume that I'll need to specify input and output codecs specifically, along with things like bitrate, or aspect ratio but this is where I come unstuck.

Any help would be much appreciated!

Answer 1

Okay now actually there needs to have a more detail of the video which fails while transcoding. But still looking at the errors, here are the tries you can do. I will warn you that there are hell lot of combinations possible for output(bitrate,framerate etc.), but all that you have to decide.

Option 1

ffmpeg -y -i ip.mkv -vcodec libx264 -acodec libvo_aacenc op.mp4

This is similar to ffmpeg -i ip.mkv op.mp4 but I added codecs explicitly.

Option 2

ffmpeg -y -i ip.mkv -vcodec libx264 -acodec libvo_aacenc -b:a 92k op.mp4

Added bitrate, which you can change as per your need.

Option 3

ffmpeg -y -i ip.mkv -vcodec libx264 -acodec libvo_aacenc -b:a 92k -r 30 op.mp4

Added fps of 30.

You can also give a try of mix of 2 and 3 option.

Hope this helps.Cheers.:)

PS: As @slhck told; please update ffmpeg first and then try these. Also all these are re-encoding commands, so if you are really going for them; use better audio encoder than I have illustrated.