The file must be in Microsoft WAV format and contain PCM data. The chart for supported media formats on Android might be helpful. So if you have AC3 encoded audio, you probably leave it at that if the device and container format supports it. DTS is a complete looser and should be also left out, like MP3. FLAC is 4th on efficiency and the most supported lossless format. Leaving out MP3, AC3 comes in third place. Multichannel mapping should be fixed in the latest LTS release (12.04, it wasn't in 10.04). The most efficient codec is HE-AAC v2 but it is not well supported in Ubuntu, due to licensing/patent issues in some countries. The situation is (still?) really messy, which is why there exist no easy to use GUI like Handbrake. Advice for codec and quality choice on multichannel audio Using -q 0.5 will result in a file larger than common AC3 6ch audio from a DVD, using -q 0.3 will cut the file size in half. This is due the techniques behind those profiles that are centered around low bitrates. HE-ACC is limited to -q 0.5, I think, and HE-AAC v2 even lower. The quality setting depends on the profile you use. You can extract the raw stream with MP4Box from the gpac package if you want to. Note that the resulting file is a MP4 with a AAC stream in a MP4 container, not a raw AAC stream. avconv -i $myfile -f wav - | neroAacEnc -q 0.3 -he -ignorelength -if -of $myencodedfile You can also use avconv (formerly known as ffmpeg, now forked and with the CLI tool being renamed) to do the conversion to WAV. If you input format is already WAV the following should work: cat $myfile | neroAacEnc -q 0.5 -he -ignorelength -if -of $myencodedfile To workaround this you need to pipe the input with another program to the encoder and use the -ignorelength parameter. It is not due to this encoder being crippleware, but how to handle large numbers in a program. ![]() One problem you will encounter with large files like 5.1 WAV is the file size limitation. Nero offers it free of charge but doesn't give support for it. This encoder is (still?) considered to be the best encoder quality wise. NeroAacEnc does support HE-AAC and HE-AAC v2 via -he and -hev2 parameters.
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