Addicted to Fun and Learning
- Sep 27, 2019
- Milwaukee, Wisconsin, USA
Is there a list of Internet Radio Stations that broadcast in Opus? Or are any doing so?
These important formats are missing:Audio Bit Rates
Audio Bit Rates and Uncompressed Files
Every second in an audio recording has a specific quantity of bits. When considering various types of sound files this is expressed as the number of kilobits of data per second (kbps). For example, a 128 kbps file has 128 kilobits stored for every second of audio. This is an example of an audio bitrate that defines the amount of data that is stored in the sound file.
Every audio file has an associated bitrate. Faster bitrates correspond to more data stored across the full frequency range. The more kilobytes that are stored per second the greater the potential for better sound quality of the file, within the limits of human hearing, for similar types of files. Uncompressed audio files include the following types:
Bitrate is determined by the sampling rate and the bit depth. The sampling rate is the number of samples taken in a second. For example, CDs have a sampling rate of 44.1kHz.
- Compact discs (CDs) have a bitrate of 1,411 kbps at a 16-bit bit depth. This was first established by Philips and Sony in 1980; and adopted as a standard in 1987.
- WAV files were developed by Microsoft and IBM to enable computers to read pulse code modulation (PCM) data. High-quality WAV files have a bitrate exactly the same as CDs at 1,411 kbps at 16 bit. However there are variations of WAV files. The actual bitrate is determined by a specific formula which multiplies the sampling rate with the bit depth and the number of channels.
- AIFF files, were developed by Apple, using the same uncompressed technology as WAV files. Much like WAV files AIFF files are another way for electronic devices to read PCM data.
When it comes to audio and bitrates, size does matter. The more kilobits per second the greater the quality of the sound. For many casual listeners, a bitrate of 320 kbps is acceptable. Clearly, CD-quality audio with 1,411kbps will sound better, particularly to discerning listeners.
PCM (pulse code modulation) is the hierarchical format for uncompressed audio. All recordings initiate as soundwaves in an analog setting. PCM converts this information into digital format by sampling recordings.
Compressed Audio Files
MP3s are a very common form of a compressed audio file, with a maximum bitrate of 320 kbps at 16 bits, substantially lower than that of the uncompressed formats. MP3s use a compression codec that removes frequencies while trying to preserve as much of the original recording as possible. This allows for reduced file sizes but sacrifices sound quality. MP3s are an example of lossy compression, because the compression scheme does not include all of the original information in the recording.
MP3s were very popular in the early days of the internet due to the small file size; enabling easier sharing across a then slower internet. MP3s are still used heavily by streaming services and digital music platforms making them one of the largest formats for DJ music.
Free Lossless Audio Codec (FLAC) is an open source compression method for audio files; with significant advantages over MP3 because original recording is unaffected by the compression (no information is subtracted). With FLAC the file size can be reduced up to 60% compared to the original uncompressed file (such as WAV).
FLAC has grown in popularity, in large part to the lack of licensing restrictions, and has become the primary way to offer compressed lossless audio. FLAC also offers extra metadata to be stored like album art which WAV files do not support.
Lossless Audio Formats
The following table depicts the more common lossless audio formats with the most relevant information:
Format Sample Rate Bitrate Type Open Source? Metadata?
WAV 44.1 kHz (usually) 1,411 kbps (usually) Lossless No No AIFF 44.1 kHz (usually) 1,411 kbps (usually) Lossless No Yes FLAC Up to 655,350 Hz 1,411 kbps (usually) Lossless Yes Yes ALAC Up to 384,000 Hz 1,411 kbps (usually) Lossless Yes Limited to ITunes WMA Up tp 96 kHz Up to 768 kbps Lossless No Yes
Although FLAC has some advantages over WAV, WAV is found in many pro audio devices that are not capable of FLAC. Clearly, lossless is preferable unless file storage capacity is of concern, or lossless isn’t available for some venue. For example, most of the internet radio stations broadcast in a lossy format.
Lossy Audio Formats
The following table depicts the more common lossy audio formats with the most relevant information:
Format Sample Rate Bitrate Type Open Source? Metadata?
AAC Up to 96 kHz Up to 529 kbps Lossy No Yes OGG Up to 192 kHz Up to 500 kbps Lossy Yes Yes MP3 Up to 48 kHz Up to 320 kbps Lossy Yes Yes
AAC is capable of the highest bitrate of the lossy formats but is not open source.
You could add a section about Bluetooth Codecs and audio quality - I do have hope we will get true lossless bluetooth in the next years - but I think with some of the advancements especially in getting stable bandwidth of > 320kpbs with Bluetooth 5.0+ the current codecs can make a difference. Obviously SBC is very primitive - but even SBC at > 300 kbps seems roughly like MP3 at 192Kbps IMO
I've always assumed it was to highlight the codecs flaws for comparison sake rather than what we should be using to maintain a portable collection. Everything in my music collection is flac, but I love to see progress gained in the lossy codec realm. Opus and xHE-AAC are incredible formats for audiobooks. Speaking of progress, look for meta's AI based codec. That codec is nuts.Even in 2014, I am not sure why anyone would bother to test sound quality at around 128kbps.
It's >256k VBR and ~850k FLAC etc you get my interest. If you listen to music at ~128k, you either don't care much about SQ or you don't love the music enough to try to do it justice...
Yes, if it cost quite a bit more for them to provide, and there isn't much profit to begin with, I am not likely to find very many of them at all.Lossless codecs by definition have variable rate. Lossy codecs can run variable or constant bit rate. Streaming services by far prefer to use constant bitrate. For this reason, they use lossy codecs. And at any rate, they tend to want to save bandwidth to keep costs low (Internet radio is not a profitable thing by itself). So I would not look for "FLAC" streaming of radio stations.
That's a rather pretentious statement...If you listen to music at ~128k, you either don't care much about SQ or you don't love the music enough to try to do it justice...
Maybe 25 years ago - I worked in a tech company with a few other music "fanatics" (not really audiophiles but we all had "big" music collections of CD for the time) - I managed to get a 30GB HDD (huge for the time I think) - we thought we might be able too pool our joint CD collection encoded on this HHD on the office network, but first we had to figure out what we codec to use and what bitrate we would need to encoded the CD's to get the SQ good enough that it would not annoys us when we were listening maybe 8 hours a day - sadly there was no opus or even AAC at the time - but we spent a week blind testing the different codecs available - these actually included the WMA encoder (which I believe @amirm was involved with) - it was very interesting exercise. We decided to pick 128kps MP3 (Fraunhasuer encoder) more for compatibility than actual sound quality but WMA at the time had the best size to SQ ratio. I seem to remember WMA 64kpbs was pretty impressive (similar to 96 kpbs MP3). We even tried MP2 (as that is roughly the same as SBC bluetooth codec as the encoded was much faster than the others) and we thought with MP2 we could need double the space for the same SQ.That's a rather pretentious statement...
Opus 128kbps is completely transparent to me, doing ABX with the best measuring gear I have. And my personal findings seem also in agreement with actual listening tests.
Would i do all this if i didn't care about SQ?
Yeah, my application is not an office environment, put pretty casual listening. My serious listening -- I will do with WAV files that are 16-bit 44.1 Kz (CD quality). But for an internet radio that I can keep on and listen while I am doing other things, I am finding that AAC 128 kbps (and higher) and MP3 at 320 kbps seem to work just fine. I haven't decided what bit rate to set as the limit for OGG or Opus yet, as I found so few radio stations using those. I am just over a third of the way to using up my 99 presets with 35 stations saved; so no problem finding genres that I like with the Skytune built into the Ocean Digital radio. I hope the Grace Digital radio that I ordered will display the bitrate, the way the Ocean Digital does. It incorporates Shoutcast, and some other methods, but I don't think it has Skytune. My Aurender server, when I use it as an internet radio, has Shoutcast, and does not display bitrate. I am not sure if there is a setting that I can change so that it will.I would struggle to tell the difference between 192 kbps AAC or 256 kbps MP3 and lossless CD quality.
I was sold on wma at the time too. 2 pass 192 ftw! I had a heated debate with a friend at the time about what to rip everything at, and he insisted on mp3 while I went wma. I still can say that I made the right choice for quality sake. Now I'm kind of sold on apple's itunes aac codec for compatibility and opus for a slight edge in quality, especially very low bitrate stuff for audiobooks. I'm pretty sure that I hear 320kbit mp3 artifacts in most orchestral music and whenever a song has chimes. I don't hear the same glassy and smearing artifacts on opus and aac.WMA at the time had the best size to SQ ratio
I also struggle to hear flaws with opus and aac at 128kbit. It really is a huge leap over mp3.Opus 128kbps is completely transparent to me, doing ABX with the best measuring gear I have. And my personal findings seem also in agreement with actual listening tests.