If you want to read more about the controversial Absolute Sound article where much of the above is discussed... Absolute Sound Forum |
Loss of precision is often a a result of floating point calculations. That is why I mentioned it. The calculations used to compress and decompress files is entirely an integer process. The program may make mistakes, but given you can convert to wav to flac and back to wav and have a bit identical file says that the conversions are being done properly. There is no evidence of any program error or loss of precision. The files before and after conversions are the same based on binary compares, not just checksums.
As to bytes versus integer, in a typical 16/44 file each datapoint is an 16 bit number, which cannot be represented by a byte. Hence, my reference to integers rather than bytes. But the real point is that the calculations do not result in any loss of precision.
The wav to flac to wav tests are just that - tests. They try to see if the conversions influence the sound. People have done this because of the reasons I stated. Some people believe the original and final wav files do sound different, even though the original and final wav file are bit for bit identical. You can say STOP, but people report that they can sound different. I am just summarizing what some people report. |
09-04-14: Kijanki
In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them.
Perhaps authors are members of mentioned AA? No doubt! If files are identical according to a binary compare, why waste time debating if they sound the same. |
In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them. Perhaps authors are members of mentioned AA? |
If people think they hear differences from all these things, who as I to say? Nothing. There will never be a consensus in anything. " When rip wav->flac->wav, depending on the software, possible loss of precision?"
That is not likely. The data is integer not floating point format. What does not floating point have to do with potential errors? It's a software program. Data is probably processed in bytes. People do binary compares, find the files identical, and report they sound different. At one point I spent a lot of time doing binary compares and looking a file formats. If binary compare returns TRUE, STOP!!! Like I said, people likes to exaggerate and sometimes have no clue in not comparing apples to apples but apples to oranges as we've seen in this forum. Some people have ripped to flac and then decided to convert to wav because they think it sounds better. Somebody then pipes in and says they should re-rip everything, since the converted wav file will not sound the same as the ripped wav file, even though they are bit for bit identical. Where's the original wav? When you rip into another format, it doesn't overwrite the orig but just create a new copy in new format. No? Let's not get too deep into this. There are lots of discussions on AA and other places about this and nothing ever gets resolved. Don't worry I won't. Have NO plans jumping in AA. |
" When rip wav->flac->wav, depending on the software, possible loss of precision?"
That is not likely. The data is integer not floating point format. And, you can compare the first and last wav files and they will be bit for bit the same. People do binary compares, find the files identical, and report they sound different. At one point I spent a lot of time doing binary compares and looking a file formats. I taught computer science for years, so I am pretty familiar with the issues here. I never found any differences in the files people claimed sounded different. It makes no sense to me that those 2 wav files would sound different, but some people have reported it.
"If file is already wav, why rip again to wav?"
Some people have ripped to flac and then decided to convert to wav because they think it sounds better. Somebody then pipes in and says they should re-rip everything, since the converted wav file will not sound the same as the ripped wav file, even though they are bit for bit identical.
Let's not get too deep into this. There are lots of discussions on AA and other places about this and nothing ever gets resolved. |
The timing in most USB connections today is controlled by the converter or the DAC, not by the PC. So, there should be no timing issues specific to the PC. All it has to do it keep the buffer full and deliver the data when asked. I guess it is possible that the USB on the PC does not handle the interrupt request from the converter/DAC correctly, but I think that is a remote possibility. In any case, that should be independent of the CPU and disk usage, unless the USB implementation is really bad.
People are concerned about electric noise on the USB ground and on the signal lines, as well as RF noise from the PC that can effect the converter or DAC. That is why the devices I mentioned earlier are available. More and more equipment has galvanic isolation on the data lines, usually in the form of small transformers. Expensive cables can be used to try to eliminate RF problems on the cable and connectors.
Using a separate +5V power supply certainly makes sense if the USB device is powered by the +5V on the USB cable. Certainly, a $500 linear power supply will be much cleaner and more stable that the signal on a USB. However, that has nothing to do with file formats, HD usage, CPU usage etc.
As to bit identify files in the same format sounding different, that makes absolutely no sense to me. In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them.
If people think they hear differences from all these things, who as I to say? For me, these effects are interesting to think about, but I don't hear most of the differences that these people report.
I did not mean to get this thread off topic, just wanted to summarize some of the issues that people discuss. |
Some people claim that 2 bit for bit identical wav files will sound different if one was ripped directly to wav and the other ripped to flac and converted to wav. Same if a wav file is converted to flac and back to wav. Makes no sense to me, but some people claim they sound different. If file is already wav, why rip again to wav? When rip wav->flac->wav, depending on the software, possible loss of precision? To confirm integrity of 2 wav files, do a binary compare. Google binary compare ... free on all platforms. Ripping is basically wrapping data into another format. Comparing flac to wav, some people claim the wav sounds better because the flac has to be decompressed and the extra CPU cycles needed to do that produce electrical noise that degrades the quality of converter or DAC conntected to the USB. On my system, the cpu runs at well less than 5% while decoding flac ... Processing a file is not CPU intensive. The most important is timing and logic (software) in processing the different file formats. Some people claim ... Some people claim they can hear speakers, DACs ... breaking in after 2000+ hours. Depending on my mood, how much wine had for dinner, time of day ... my system sounds different. Is this system breaking in or just product of the environment? |
Knghifi, I cannot hear the difference between different
formats or sources but it might be related to jitter
suppression in my DAC. Jitter might be related to amount of
electrical noise in the system making it difficult to
compare since this noise is changing. Radio stations have
to cut power at certain time, possibly at 6PM by FCC rule
(since propagation at night is much better). Testing one
file vs identical file before and after 6PM could result in
different sound.
Dtc, It is possible that decompressing or compressing file
that is being played somehow affects the timing but once
files played have the same checksum they have to sound the
same no matter how many times converted before. Badly
fragmented HD wouldn't change the timing since timing is not
attached yet (it is data) while HD is at least 1000x faster
than necessary to deliver this data (while data goes thru
buffers) but might possibly change amount of electrical
noise drive produces. It is far fetched but I've learned
not to question what other people can or cannot hear
especially when younger and/or musicians (trained ears). |
Some people claim that 2 bit for bit identical wav files will sound different if one was ripped directly to wav and the other ripped to flac and converted to wav. Same if a wav file is converted to flac and back to wav. Makes no sense to me, but some people claim they sound different.
Comparing flac to wav, some people claim the wav sounds better because the flac has to be decompressed and the extra CPU cycles needed to do that produce electrical noise that degrades the quality of converter or DAC conntected to the USB. On my system, the cpu runs at well less than 5% while decoding flac. Hard for me to understand how that changes a galvanically isolated DAC. I can understand that they will be a difference if the computer is controlling the timing. But in most cases today the external device is controlling the timing. The computer just needs to have a full buffer.
Different file layouts should not change the sound, unless you believe that the minute differences in how the CPU processes them causes a change in the connected equipment. The bits delivered to the buffer are identical for flac versus wav. Again, I am assuming the converter or DAC is controlling the timing.
Personally, I do not hear these differences. I just wanted to help the OP understand the issue.
There are also now devices on the market that try to completely isolate the USB signal lines and the ground from the PC. They also provide a separate 5V supply, independent of the computer. These devices may help if you have a particularly noisy PC or a poorly implemented DAC or converter. Some people swear by these devices, others ignore them. |
Kijanki - I assume bit perfect software/hardware delivery is a given. I am talking about different sound from bit identical files. There is no timing information in a digital file so the jitter comes on playback. There are lots of sources of it, as you say. But, how do you get different jitter from 2 identical files played back on the same system? It is theoretically possible, for example, if one file is contiguous and the other is badly fragmented and you computer and disk drive are really noisy. But if two bit identical files are contiguous and on the same platter on the same drive, some people will still say they sound different. That is the part I just cannot hear. Can you? Are you talking about identical same format files (flac vs flac) or different format (flac vs wav)? If same format, they should sound the same. Different format, then probably sound different since they are encoded differently even though both are lossless and uncompressed ... different file layout. |
Kijanki - I assume bit perfect software/hardware delivery is a given. I am talking about different sound from bit identical files. There is no timing information in a digital file so the jitter comes on playback. There are lots of sources of it, as you say. But, how do you get different jitter from 2 identical files played back on the same system? It is theoretically possible, for example, if one file is contiguous and the other is badly fragmented and you computer and disk drive are really noisy. But if two bit identical files are contiguous and on the same platter on the same drive, some people will still say they sound different. That is the part I just cannot hear. Can you?
Let's not take this thread down the road of debating all those issues, unless the OP wants to. There are certainly endless threads on that topic I just wanted to explain to him some of the issues that are so often debated. |
Dts, Digital files can sound different in spite of being "bit perfect". The main and only reason for that is jitter - a variation in time that converts into noise. Jitter creates sidebands that are at very low level but still very audible since not harmonically related to the signal. Jitter is a main problem of digital playback. It can be generated by the source, digital cable or the DAC itself. It is pretty much system dependent. |
NAB2 - those discussions never reach a conclusion. There are people who insist that two bit for bit identical files sound different. There are people that think that flac always sounds worse than wav. There are people that think that a wav file that has been converted to flac and back to wav will sound different. There was even a controversial 4 part article in the Absolute Sound that found sound differences in pretty much every conceivable way to produce bit for bit identical files.
Who knows what is going on, buy there is a small group of people who are absolutely convinced of these differences, but most people cannot hear the differences on their systems. Its kind of like expensive power cables, little silver cups, myrtle wood blocks, etc. You can spend your life looking for these differences or you can listen to the music. Just depends on which part of the hobby most interests you.
You might want to spend some time experimenting. Most of us have. I must say getting a new Chord Hugo DAC swamped any possible improvements in wav versus flac, etc. |
Just ripped over 600 CD's using Dbpoweramp Batch Ripper with the Nimlie USB Plus, and an old PC. Took about 3 days. Load 100 CD's at night, in the morning they're ripped.
Let me know if interested. |
I've scanned it and will read it carefully soon. Is there a bottom line in that discussion? Seems like it was one opinion against another. Did you reach a conclusion? |
You might find this thread I started in AudioAsylum interesting:
http://db.audioasylum.com/mhtml/m.html?forum=digital&n=172907&highlight=rip+dull&search_url=%2Fcgi%2Fsearch.mpl%3FForumSelect%3DSelected%26searchtext%3Dcbs%2B6sn7gtb%26SelectForumtubes%3Dtubes |
Thanks for the answers. I've used both Exact Audio Copy and dBpoweramp for ripping my CD's but was concerned. As Dtc noted there used to be reviews on the quality of the drives and Plextor came out on top. My current drive is a Plextor, but thought (apparently mistakenly,)that the quality of the drive might have something to do with the quality of the rip. I see the logic of "digital" ripping being independent of the CD drive in the computer, but it doesn't feel right.
I usually rip to WAVE rather than FLAC, but have done both. Perhaps for the same reason (feelings over reason).
Thanks. |
RL, So far I am using mostly MusicBrainz Picard to autotag FLAC after ripping. Is there a tool from dbpoweramp vendor that enables tagging similar to while ripping that automatically pulls best metadata from the 4 multiple metadata DBs dbpwoeramp rip software uses?
Musicbrainz/Picard is a great tool but only uses Musicbrainz and none of these DBs seem to always trump the other. Each has different content available and tagging works best by using multiple source DBs still these days it seems/ |
Ain't it funny how a $50 computer CD drive does a better job of ripping CDs than a $10,000+ "audiophile" player?
And yes, dbPowerAmp is the bee's knees of CD ripping software. It also does a heckuva job transcoding ripped discs to other formats like FLAC, etc.
Long story short, Nab2, your PC's CD drive coupled with dbPowerAmp will do a fantastic job of ripping your CDs - end of story...
-RW- |
Good software for ripping is the key. End of story.
For .wav on WIndows, I found free Windows MEdia Player included in Windows to work very well in general for many years.
I am in trial period with DBPoweramp for ripping to FLAC starting last night with a few CDs ranging from very good to questionable condition. IT provides a lot of useful information and options for ripping. It resorted to a block rip mode for a few tracks on CD that were apparently damaged. This was dog slow when it occurred and I had to skip those tracks. It seemed fast and reliable under most circumstances though. ALso the way it auto tags using multiple database sources and provides supplemental album art choices off the internet as a contingency when needed is the best I have seen so far for tagging at rip time. I would pay to use this over EAC I think in that my recollection is EAC auto tagging may not be as sophisticated? Mediamonkey RIP to FLAC has not floated my boat at all to-date in terms of speed and overall user friendliness, especially for tagging. |
The transport in a CD player has to deliver the bits without retries for data errors given the need to deliver the bits in real time. The drive in a computer is not under any real time constraints, so it can resample as much as necessary to get an exact copy, as long as the CD is not really damaged. In fact, the computer drive should do a better job of insuring that all the bits are correct.
That said, there used to be regular reviews of drives for ripping. Not sure if those reviews are still being done or not. In the early days, everyone swore by Plextor drives. But they have not been made since 2005 or so. Latter Plextor drives were just re-badged from large suppliers.
Using a ripper like dBpoweramp you should have no trouble with pretty much any drive in your computer. dBpoweramp will also check your rip against other people's rips, which is an added level of assurance. |
Quality of computer CDP has nothing to do with it. Get good ripping software like MAX or XLD for Mac or EAC for Windows. Ripping program reads CD as data instructing CDP to re-read given sector multiple times until proper checksum is obtained. MAX (free) that I use allows to set number of attempts. I set it to "Do not allow to skip" that will guarantee that extracted data is identical to original CD. Some ripping programs even allow you to compare overall CD checksum with database.
CDP operates differently - most of them cannot read the same sector twice because they operate in real time. For small scratches within 4mm along the track they error correct it, between 4-8mm they interpolate missing sector and skip for scratches longer than 8mm.
Also notice, that ripped CD is stored on HD as data (no timing). |
Your entire premise is misguided. The optical disk drives in any recent vintage computer is of sufficient quality to do a superb job at reading the data from a musical CD disc. The ripping software you choose to use has far more effect on the quality of the rips. |
