iTunes 256 kbps burned to disc.

When people say that most human ears can't tell the difference between 256 kbps and higher bitrates, do they just mean on smaller devices? If they were to burn to a blank cd, a purchased 256 download, or even a cd that was ripped to 256, would the newly burned cd be different to the ears than the original store bought cd?

 

I can usually tell the difference between a lossless CD and lossy files burned to CD. For me the lossy file CD is usually lighter in the bass.

 

When I started to create my iTunes library about 10 years ago it was solely for use with an iPod and I created the library with lossy files. I thought the whole thing was terrific. I was doing a bit of business travel and used Bose noise cancelling headphones. About two years later I started getting into the idea of listening to files on my computer through my Audio system. The first go was pretty disappointing. The sound was lifeless. Then I started reading about lossy versus lossless files. I didn't have much hard drive space back then and creating those large files had me wondering. I ripped about 50 CDs to Apple Lossless. The next time I played those files through my system there was finally hope that this could be a reasonable alternative. Adding an external DAC about a year later and now it was the real deal.

I've not gone back and compared lossy files to lossless since that time and I don't feel the need to. I'm convinced. Within the past year though I helped a friend set up his system to play his files. I also showed him how I rip files and help him add a bunch of stuff to his library. Once while I was over there and he was telling me how much he was enjoying his new system he said "but why is it that the files you ripped for me sound so much better that the files I had in my library?" I told him I think I know but let's check. Obviously his files were lossy. The ones I did were not.

If others cannot hear a difference or beleive there is no discernible difference between. High bit rate lossy files and lossless files I would never challenge what you hear and believe but I'm solid with what I have done and continue to do.

 

A lot also depends on the environment you are listening in as well. A good pair of headphones and possibly using a DAC should make the difference in files pretty obvious. If you are listening in a car and it is not a high end system then 320 kbps is probably good enough most people would not be able to hear the difference.

 

I would agree that any kind of mobile/portable environment 256/320 are probably fine. The times that I play music from my iPhone or iPad through my car system or via my earbuds I never stop and think man that sounds awful but then my car system and earbuds are pretty run of the mill so others might be more discerning in those situations

 

you know, for all these questions you've been asking about the percieved quality of digital music, the ultimate answer is always going to be 'your mileage may vary.'

everyone's ears are different. some people can tell the difference between 320k mp3s and their lossless source. meanwhile, other folks can't tell the difference between 192k mp3s and lossless. and for many, these perceptions change over time. you may start out being unable to discern between files, but as you get acclimated to listening to both lossy and lossless sources, you might start to hear certain things or be unconsciously drawn to one over the other. all of this is perfectly fine. it's a process.

you'll get lots of useful advice here, but ultimately, you have to use your own ears as a guide. if you want to do a shootout to satisfy your curiosity, go for it. rip some tracks you enjoy both as lossless and as mp3s or AACs, at whatever bitrate, and have a friend switch between them as you listen without looking. use the setup(s) you'd normally use to listen to music. see what you notice, see what you like and dislike. you may be surprised.

there is no right and wrong when it comes to perception of SQ. the goal is to find whatever arrangement helps you personally to get the most enjoyment out of your music. after all, the music is the whole point. (...theoretically.)

 

I was under the impression that a CD, whether burned or manufactured, is always the same bit rate? Because of the format being the same?

 

It is, but it can't 'upgrade' a lossy source.

 

Yes, but if you burn a CD from a lossy file you are, effectively, upsampling to CD standard. However, this process doesn't artificially recreate missing data, it just converts the same data to a different (larger) file type.

 

I see

 

So the old maxim, "You're only as good as your source" rings true.

 

+1 to the responses above. you can't retrieve lost data once gone by re-encoding a lossy file at a higher resolution, including into lossless formats. I used to run across mysteriously tiny, phasey-sounding files at '256kbps' frequently, but people seem to have stopped doing this.

for completeness' sake, I just wanted to mention that redbook CD audio, being an uncompressed standard, has no 'bitrate' associated with it. it does have bit depth (the '16' part of 16/44.1), but that's an entirely different type of measurement. here's a post from a couple months ago that goes into greater detail if you're interested in the exciting world of digital audio resolution.

 

Until you know what to listen for (and care enough to listen for it), you probably won't be able to tell the difference.

Midrange masking is how lossy algorithms work their magic. If one sound is momentarily louder than another in the midrange, the algorithm assumes that listeners don't need to hear the softer sound. Most listeners don't listen that critically. But for those of us who do, tracking a subtle part that drops in and drops out is easy to detect, and quite annoying.

And yes, the bass might also suffer a bit with the lossy version.

 

Whether or not someone can HEAR this difference should be irrelevant to the answering of the question. If you buy a 256AAC and make a redbook CD, they will both sound exactly the same. NEITHER will sound like the CD you buy retail.

 

On my Sony BD-S390, the display shows a bitrate of over a 1000kb/s when playing a Red Book CD....

http://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio#Bit_rate

 

If my logic is correct, the fact red book CD has a bit rate of something like 1200kbps, is the reason it sounds better than a 320kbps Mp3? Probably more complicated than that, hey ho

 

I burn CDs for the car from iTunes that I ripped at 256, and they sound fine for me.

 

That's the gist, yes. Basically, it includes all (although this is subject to debate) the information you need to hear the music. Lossy formats - as the name implies - are smaller file size formats that are created by taking out a lot of this information.

Think of it like this: you get a cake in a box. You take it out to put it in a smaller box. It's too big, so you cut it down until it fits in the smaller box.

You could, if you wanted to, put it back in the bigger box but you won't recover the bits of cake you've cut off - the smaller cake will just live in a bigger box.

 

The question is how much the cut-off bits can even be tasted.

 

Well yeah, that's the nub of the issue really.

 

that's correct. technically, redbook CDs can be evaluated to have a 'bitrate' of about 1.4mbps (or 1411200 bits per second, to be exact).

the post I linked to addresses in more detail how this can be, but in a nutshell, bitrate stops being a very useful measurement of SQ when discussing data that isn't compressed. it's a unified expression of throughput for one second of audio, so it's very helpful in evaluating compression algorithms. it's not so useful in comparing the sound of uncompressed audio because that data is fully two-dimensional. bit depth and sample rate (16 bits and 44.1khz respectively, for CDs) both affect sound in independent ways. though you can derive a 'bitrate' whenever both those numbers are present, that number itself isn't a very meaningful representation of what you'll hear.

 

I must confess, I struggle to get my head round the different between bit rate and sample rate. I'm sure it's very simple and very obvious but I have a blind spot.

 

I burn CDs for non-critical listening in an inferior noisy environment (the car) from mp3s of bit rates as low as 160kbps. And to be honest, they sound fine.

On headphones, or through a good home system? Sure, I can tell the difference. But in a car, they sound fine.

 

Take a read:

BITRATE

In digital multimedia, bitrate represents the amount of information, or detail, that is stored per unit of time of a recording. The bitrate depends on several factors:

• The original material may be sampled at different frequencies.
• The samples may use different numbers of bits.
• The data may be encoded by different schemes.
• The information may be digitally compressed by different algorithms or to different degrees.

Generally, choices are made about the above factors in order to achieve the desired trade-off between minimizing the bitrate and maximizing the quality of the material when it is played.

If lossy data compression is used on audio or visual data, differences from the original signal will be introduced; if the compression is substantial, or lossy data is decompressed and recompressed, this may become noticeable in the form of compression artifacts. Whether these affect the perceived quality, and if so how much, depends on the compression scheme, encoder power, the characteristics of the input data, the listener’s perceptions, the listener's familiarity with artifacts, and the listening or viewing environment.

The bitrates in this section are approximately the minimum that the average listener in a typical listening or viewing environment, when using the best available compression, would perceive as not significantly worse than the reference standard:

Audio
CD-DA
CD-DA, the standard audio CD, is said to have a data rate of 44.1 kHz/16, meaning that the audio data was sampled 44,100 times per second and with a bit depth of 16. CD-DA is also stereo, using a left and right channel, so the amount of audio data per second is double that of mono, where only a single channel is used.

The bit rate of PCM audio data can be calculated with the following formula:


For example, the bit rate of a CD-DA recording (44.1 kHz sampling rate, 16 bits per sample and 2 channels) can be calculated as follows:


The cumulative size of a length of PCM audio data (excluding a file header or other metadata) can be calculated using the following formula:


The cumulative size in bytes can be found by dividing the file size in bits by the number of bits in a byte, which is 8:


Therefore, 80 minutes (4,800 seconds) of CD-DA data requires 846,720,000 bytes of storage:


MP3
The MP3 audio format lossy data compression. Audio quality improves with increasing bitrate:

• 32 kbit/s – generally acceptable only for speech
• 96 kbit/s – generally used for speech or low-quality streaming
• 128 or 160 kbit/s – mid-range bitrate quality
• 192 kbit/s – a commonly used high-quality bitrate
• 320 kbit/s – highest level supported by MP3 standard

Other audio

• 800 bit/s – minimum necessary for recognizable speech, using the special-purpose FS-1015 speech codecs.
• 1400 bit/s – lowest bitrate open-source speech codec Codec2.[17]
• 2.15 kbit/s – minimum bitrate available through the open-source Speex codec.
• 8 kbit/s – telephone quality using speech codecs.
• 32-500 kbit/s – lossy audio as used in Ogg Vorbis.
• 256 kbit/s – Digital Audio Broadcasting (DAB.) MP2 bit rate required to achieve a high quality signal.[18]
• 400 kbit/s–1,411 kbit/s – lossless audio as used in formats such as Free Lossless Audio Codec, WavPack, or Monkey's Audio to compress CD audio.
• 1,411.2 kbit/s – Linear PCM sound format of CD-DA.
• 5,644.8 kbit/s – DSD, which is a trademarked implementation of PDM sound format used on Super Audio CD.[19]
• 6.144 Mbit/s – E-AC-3 (Dolby Digital Plus), which is an enhanced coding system based on the AC-3 codec.
• 9.6 Mbit/s – DVD-Audio, a digital format for delivering high-fidelity audio content on a DVD. DVD-Audio is not intended to be a video delivery format and is not the same as video DVDs containing concert films or music videos. These discs cannot be played on a standard DVD-player without DVD-Audio logo.[20]
• 18 Mbit/s – advanced lossless audio codec based on Meridian Lossless Packing.

Video

• 16 kbit/s – videophone quality (minimum necessary for a consumer-acceptable "talking head" picture using various video compression schemes)
• 128–384 kbit/s – business-oriented videoconferencing quality using video compression
• 400 Kbit/s YouTube 240p videos (using H.264)[21]
• 1 Mbit/s YouTube 480p videos (using H.264)[21]
• 1.15 Mbit/s max – VCD quality (using MPEG1 compression)[22]
• 2.5 Mbit/s YouTube 720p videos (using H.264)[21]
• 3.5 Mbit/s typ – Standard-definition television quality (with bit-rate reduction from MPEG-2 compression)
• 4.5 Mbit/s YouTube 1080p videos (using H.264)[21]
• 9.8 Mbit/s max – DVD (using MPEG2 compression)[23]
• 8 to 15 Mbit/s typ – HDTV quality (with bit-rate reduction from MPEG-4 AVC compression)
• 19 Mbit/s approximate – HDV 720p (using MPEG2 compression)[24]
• 24 Mbit/s max – AVCHD (using MPEG4 AVC compression)[25]
• 25 Mbit/s approximate – HDV 1080i (using MPEG2 compression)[24]
• 29.4 Mbit/s max – HD DVD
• 40 Mbit/s max – 1080p Blu-ray Disc (using MPEG2, MPEG4 AVC or VC-1 compression)[26]

Notes
For technical reasons (hardware/software protocols, overheads, encoding schemes, etc.) the actual bit rates used by some of the compared-to devices may be significantly higher than what is listed above. For example, telephone circuits using µlaw or A-law companding (pulse code modulation) yield 64 kbit/s.

SAMPLE RATE

Sample rate is the number of samples of audio carried per second, measured in Hz or kHz (one kHz being 1 000 Hz). For example, 44 100 samples per second can be expressed as either 44 100 Hz, or 44.1 kHz. Bandwidth is the difference between the highest and lowest frequencies carried in an audio stream

 

One thing to remember in this equating of bitrate with audio quality is that lossless audio formats such as FLAC, ALAC, etc., may display a smaller bitrate during playback on devices that support them but their quality is equal to the source. They contain the same 1s and 0s, bits and bytes, etc. If any difference is heard (that's not accounted for by possible expectation bias) then there's something wrong with the playback gear.