Effects of Compression

[MrLaRotta]

What program did Jmac used to make those graphics?

[speedracerx]

I have spent the last 3 days throwing a study on my Phatnoise media package for my Kenwood 789 hu. I have not allowed myself to explore compressed fileing tell this week so I'm cramming now. I loaded all my WMA files and ripped 80 cds at several speeds and settings the last 3 days (need sleep) and made several discs with samples of each on same disc. Mostly I just have more questions now than before but I dig the voice navigation.

[speedracerx]

One thing that threw me was the VRP option. Manual says this: Variable Bitrate vs Constant Bitrate Encoding
The PhatNoise Media Manager uses Constant Bitrate Encoding (CBR) by default. Variable Bitrate Encoding (VBR) is a more efficient way of encoding. Variable Bitrate Encoding ensures high audio quality throughout the MP3 file by making intelligent bit-allocation decisions during the encoding process. This means that the encoder will determine what bitrate to use depending on the complexity of the audio signal. It will use more bits when necessary and use fewer bits when appropriate. The VBR Quality setting determines the ratio of high/low bitrate audio frames (a frame is 1/75th of a second of audio data) The higher the VBR Quality, the higher the sound quality of the MP3 file. VBR encoding requires more processing power, so it takes a little longer. When I started useing the VBR at 320 Kbps, it took about 30 sec. per song as apposed to - well alot more with CBR at 190. I never went back to the CBR to side by side check quality - so am I correct in assuming VBR = more quality, cause I understood it said its slower and my ripps were 10x faster.

[adam71]

One thing that threw me was the VRP option. Manual says this: Variable Bitrate vs Constant Bitrate Encoding
The PhatNoise Media Manager uses Constant Bitrate Encoding (CBR) by default. Variable Bitrate Encoding (VBR) is a more efficient way of encoding. Variable Bitrate Encoding ensures high audio quality throughout the MP3 file by making intelligent bit-allocation decisions during the encoding process. This means that the encoder will determine what bitrate to use depending on the complexity of the audio signal. It will use more bits when necessary and use fewer bits when appropriate. The VBR Quality setting determines the ratio of high/low bitrate audio frames (a frame is 1/75th of a second of audio data) The higher the VBR Quality, the higher the sound quality of the MP3 file. VBR encoding requires more processing power, so it takes a little longer. When I started useing the VBR at 320 Kbps, it took about 30 sec. per song as apposed to - well alot more with CBR at 190. I never went back to the CBR to side by side check quality - so am I correct in assuming VBR = more quality, cause I understood it said its slower and my ripps were 10x faster.

Agreed.

I use EAC with Lame encoding via the Ubernet standard and have never looked back.

[Mugen]

I just use 192kbps for all my music and it sounds the same to me whether in my truck, on my PC, or on my home speakers (Primus 250s). I can usually tell if a song's at 128kbps, which is why I hate XM, it's really low quality (or my mom's car speakers REALLY suck).

[Motovet]

I take it XM is 128kbps then. Can one download at higher rates from I Tunes and similar sites? Also can one copy CD's to Ipods at higher rates? I am a total noob with the new stuff. Thanks.

[adam71]

I take it XM is 128kbps then. Can one download at higher rates from I Tunes and similar sites? Also can one copy CD's to Ipods at higher rates? I am a total noob with the new stuff. Thanks.

I have no clue what XM is. You can't download from them so it doesn't really matter. XM quality depends on the system you're listening to it through.

[PRIVATEpastry]

I'm not sure what XM is, but I'm pretty sure that its less than 128kbps. Yes, you can download at higher rates on Itunes and other download sites. You can also copy CD's to your Ipod at higher rates, but keep in mind that the higher bitrate the audio file is at, the more space it will take up on both your computer and your Ipod.

[Motovet]

I wasen't interested in recording xm, just curious what rate they air at as my Alpine XM actually sounds pretty fair. Been considering an Ipod if it can sound better than my XM reception, and tunes can be transferred at higher rates which your telling me is possible. How do you calculate play time for 4g and 8g ipods at different rates? Thanks for the info guys.

[adam71]

I'm not sure what XM is, but I'm pretty sure that its less than 128kbps.

I seriously doubt that. When I had my system in my recently deceased Grand Am which was nice sounding system the XM sounded really good. Not CD quality like they try to say it is but wayyyy better than 128kbps Mp3 quality.

[Motovet]

What Mp3 rate do you consider closest to the XM? My XM sounds real nice to me too.

[PRIVATEpastry]

I seriously doubt that. When I had my system in my recently deceased Grand Am which was nice sounding system the XM sounded really good. Not CD quality like they try to say it is but wayyyy better than 128kbps Mp3 quality.

I'll quote NetPedia (http://www.netipedia.com/index.php/XM_Satellite_Radio):

Audio channels on XM are digitally compressed using the aacPlus codec from Coding Technologies for most channels, and the AMBE codec from Digital Voice Systems for some voice channels. Due to bandwidth restrictions and a large channel load, the maximum bitrate XM broadcast from its satellite per music channel is limited to 64kbps.

And the talk channels are obviously going to be lower quality, I'm guessing 32kbps.

[pikers]

I seriously doubt that. When I had my system in my recently deceased Grand Am which was nice sounding system the XM sounded really good. Not CD quality like they try to say it is but wayyyy better than 128kbps Mp3 quality.

Just lost a lot of credibility on that one.

[adam71]

Just lost a lot of credibility on that one.

Before XM started adding wayyyy too many channels their quality was better than 128kbps. I had no idea they had changed it at the time. I was corrected but hardly at a loss of credibility as you have done to yourself by bringing up a 5 month old post.

Did you even read the date on that last post?? Asshat.

[sportyaccordy]

Can someone put up the original pictures?