trying to understand audio conversions

[miklg21]

So I have a Apple Tv I'm trying to convert my DVD's to a file that can pass the 5.1 AC-3 surround sound through the digital cable to my receiver.

Right now the only way I can get it to play one the way I like is by using Handbrake. I use the H.264 encoder which saves it as a .M4V and keeps the audio track in AC3. I have a clip from a movie so my conversions are short so I don't have to waist time with test.

I end up with a file that looks like this.

General
Complete name : C:\Users\mike\Desktop\cars1.m4v
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 60.4 MiB
Duration : 7mn 54s
Overal bit rate : 1070 Kbps
Encoded date : UTC 2008-06-15 16:02:45
Tagged date : UTC 2008-06-15 16:11:07
Writing application : HandBrake 0.9.2 2008022300

Video
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L5.1
Format settings, CABAC : Yes
Format settings, ReFrames : 1 frame
Codec ID : avc1
Duration : 7mn 54s
Bit rate mode : Variable
Bit rate : 621 Kbps
Width : 720 pixels
Height : 400 pixels
Display aspect ratio : 16/9
Frame rate mode : Variable
Frame rate : 23.976 fps
Minimum frame rate : 23.976 fps
Maximum frame rate : 23.988 fps
Colorimetry : 4:2:0
Scan type : Progressive
Bits/(Pixel*Frame) : 0.090
Stream size : 35.1 MiB
Writing library : x264 core 58 svn-736M
Encoding settings : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=4 / brdo=0 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=0 / cqm=0 / deadzone=21,11 / chroma_qp_offset=0 / threads=3 / nr=0 / decimate=1 / mbaff=0 / bframes=0 / keyint=240 / keyint_min=24 / scenecut=40(pre) / rc=crf / crf=25.5 / rceq='blurCplx^(1-qComp)' / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / ip_ratio=1.40
Encoded date : UTC 2008-06-15 16:02:45
Tagged date : UTC 2008-06-15 16:11:07

Audio
Format : ac-3
Codec ID : ac-3
Duration : 7mn 53s
Bit rate mode : Constant
Bit rate : 448 Kbps
Channel(s) : 2 channels
Sampling rate : 48.0 KHz
Resolution : 16 bits
Stream size : 25.3 MiB
Encoded date : UTC 2008-06-15 16:02:45
Tagged date : UTC 2008-06-15 16:11:07



Now when I look at that info I see only 2 channels, but when I play it on the AppleTv my receiver shows a digital audio signal and says it Dolby digital 5.1.

So if it is only 2 channel how am I getting DD 5.1?

thanks

[foxyshadis]

DD 5.1 is only two physical channels, the 5.1 is mixed into them and mixed out on playback. Look up technical information on DD. You can reencode the 5.1 as discrete channels, in something like AAC, but handbrake won't normally.

[SeeMoreDigital]

Crappy container ID support may also be the reason why MediaInfo is only able to identify the "AC-3" stream as having 2 channels.....

[2Bdecided]

DD 5.1 is only two physical channels, the 5.1 is mixed into them and mixed out on playback. Look up technical information on DD. You can reencode the 5.1 as discrete channels, in something like AAC, but handbrake won't normally.Dolby Digital 5.1 is discrete 5.1. Maybe you're thinking of Dolby Stereo / Pro Logic?

AC3 can be anything from 1.0 upwards.

The reported 2.0 here seems strange if the reported bitrate is correct.

Cheers,
David.

[todaystudy]

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