DTS 5.1 to AAC/M4A 5.1?
Reply #6 – 2009-12-26 13:12:29
That's exactly why I tried to get the 6chWAV first, so that I could use the Winamp's built in HE-aac encoder to do the job. It never let me down before, although I never actually tried doing 5.1 before. So now I'm actually reconsidering to throw away 5.1 and simply downmix it to stereo, or maybe 2.1 'cause that's my speaker config. I cannot change the bitrate of the audio without decreasing the video bitrate, and furthermore, using vbr will mean that there might be a lot of difference between the video files' quality since the filesize has to be exact, for the purpose of backing up to DVDs. Well, thanks for all the answers, perhaps in time I'll try again -q 0.100 in NeroAacEnc will yield an aproximated 64kbps encoding. If it doesn't hit the 64kbps mark, you can decrease the value by 0.001 until reaching the desired target. Maybe -q 0.098. It's still recommended because it will use more bitrate when needed by the audio complexity and less when less complex audio. I would recommend you to go 2.0ch on this, as 6ch will sound bad so there will be really no benefit from having a surround track. Don't do 2.1 downmixing, no such thing in the speakers realm, except for very specific systems, but 2.1 PC speakers are not 2.1. The #.# designation translates as number_of_fullrange_ch . n_of_non_fullrange_ch , meaning that the number BEFORE the dot is the number of discrete full range channels, while the number AFTER the dot is the number of discrete non-full range channels. That's why we can say 5.1ch or 6ch, since there are 6 channels in total, whether they're all full range or not. The so called 2.1 speaker systems are not so, as none of them are full range speaker s but limited-range ones. The smaller ones are high frequencies range speakers while the subwoofer is a low frequencies range one. So the apropiate designation is 0.3 speakers: zero full range speakers/3 limited range speakers. All that 2.1 speakers do is to send all the low frequencies to the subwoofer, so even if you create a properly mixed 2.1 downmix (2 full range channels + 1 limited range channel) and have the hardware to send a 3 channel signal to these speakers, the low frequencies from the 2 full range channels will be sent to the low frequencies speaker, not forgetting that these speaker systems don't even have inputs for all 3 channels. The same way most home-theaters are 0.6 speaker systems as none of the main speakers can carry the full range of frequencies they should to be full range speakers. They are ALL limited range speaker systems. To sum it up, do a 2ch downmix, you can with this syntaxeac3to C:\yourfile.dts stdout.wav -down2 | neroAacEnc.exe -cbr 64000 -he -if - -of C:\yourfile.mp4 or -q 0.240~0.250eac3to C:\yourfile.dts stdout.wav -down2 | neroAacEnc.exe -q 0.250 -if - -of C:\yourfile.mp4