Re: Advice to an audiophobe -- If others need it.
William Case wrote: Hi; With special thanks to Tim and David, I have read and assembled a list of audio explanation sites. Tim and David gave me enough context so that when I read (or re-read) the information at these sites, things began to make sense. I have copied the list of sites I have used for anyone else who might be as befuddled as I was. I have tried to put them into some logical order. I'm a classical musician who obviously also has an interest in this subject. If there's not a separate list for discussion of it, I'd like to create one (I run a mailing list server). But I'm not going to be the only member. Anyone interested? --Russell -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: Advice to an audiophobe ??
William Case wrote: On Wed, 2008-12-24 at 08:30 +1030, Tim wrote: On Tue, 2008-12-23 at 10:55 -0500, William Case wrote: ... 1. Gives me a whole range of adjustments for different channels. (I assume channels means different sources e.g. Master, Headphone, PCM etc.). Just to clarify, a source device generates an audio signal( line in, PCM (pulse code modulation = wav uncompressed audio), that might then get processed (eg volume control, master, headphone), and then sent to a destination (often an output device like a speaker connector or headphone jack). Because a typical soundcard has an internal hardware mixer, it can usually mix together various inputs (sources) like CD input, mic input and recorded audio signals, and produce a single output signal (mostly in stereo=2 channels). When mixing together externally received signals, no main CPU processing power is used, unless you are trying to record to hard disk etc. 2. gives me two choices and 3., 4., 5. gives me only Master. Which should I choose and why? capture means recording - usually from a line in (eg from a vcr or mp3 player etc), or from a microphone. So exclude those from your choice. If I should be using HDA NVida (Alsa-mixer), why do I have PulseAudio options? Consider pulse audio to be a real-time digital mixer and volume control, where the audio calculations are performed inside your main CPU. In the default setup, once pulseaudio has done it's processing, it passes the result to the alsa driver which outputs the audio data to the soundcard. The soundcard turns the digital audio data into analog audio signals for use with amplifier, speakers, or headphones. Pulseaudio also has enhanced capabilities like remembering that when you playback with xmms that you like to output via your amplifiers and speakers, but when you are viewing a flash video, to playback into your headphones instead, at a different level. Another capability let's you choose the destination playback device while the material is actually being played. A third capability let's the output go to an audio device on another machine. Obviously, this is a bit trickier to set up. ... These individual mixer input controls should normally be left off if you never use them, as they can each introduce noise (hiss, beeps and burbles, etc.) to the system. I will turn them off except for Master and Front. I will experiment with PC Speaker. Of course these are only available to me if I use the default alsa mixer setting. It's not a one or other setting, both parts will still be involved; pulseaudio will process, mix, and attenuate sound signals, whereas alsa will drive the physical hardware. The setting you are seeing lets you decide whether to control the physical driver volume levels or the software generated pulseaudio volume controls. If you mute or turn the alsa master way down, it wont matter how high you turn the pulseaudio mixer, since the alsamixer comes after the pulseaudio one in the audio chain. (also true for the reverse). If you play back a loud audio file, and turn both the pulseaudio source and master up full. Then change to the alsa setting. You can then use the also setting to set up an absolute maximum level that you would want to hear, by adjusting the master. Then you could go back to the pulseaudio setting to adjust the playback to a comfortable setting, and from then on only use the pulseaudio setting. ... * How is sound related to video ? Sound is the sound, video is the picture... The question is too vague to be answerable. In digital format, sound and vision are both represented with digital 1's and 0's. With all video and audio file types, there is a packing together of the audio and video information into the one file. The multiplexed file provides information about when to playback each frame of video in relation to the audio in the file. For example, an mpeg2 (dvd) file might have two frames of video, then 2 of audio, then 1 of video, two audio in an order to achieve a consistent throughput of audio and video data. * Why are there so many files associated with producing sound? In digital audio, the most basic file type is waveform (.wav), where each momentary value of audio is stored, on a 1 for 1 basis. Experiments and calculations can show us that for something we store as quality musical recording we need to sample that momentary value at 44kHz (times per second) or higher so as not to disrupt our digital recording with audio aliases. Since we also seem to enjoy the spatial enhancement produced by stereo or more channels, the file needs to store both left and right information. Finally, we found that if we only store the digital value using a small no of bits per sample, when played back we hear a harsh, chunky sound, rather than the CD like quality of using 16 (or more) bits per sample. The catch with all that is it takes up a lot space. To solve space
Re: Advice to an audiophobe ??
David, Thank you; If you cut and pasted these answers, I would love to know where (or what site) you got them. If you took the time to write them off the top of your head, I doubly thank you. You have given me enough information to do some proper research of my own particular questions and do a small write up for my own use. Ps. I am top posting because there is no other place to appropriately express my thanks. On Fri, 2008-12-26 at 01:04 +1100, David Timms wrote: William Case wrote: On Wed, 2008-12-24 at 08:30 +1030, Tim wrote: On Tue, 2008-12-23 at 10:55 -0500, William Case wrote: ... 1. Gives me a whole range of adjustments for different channels. (I assume channels means different sources e.g. Master, Headphone, PCM etc.). Just to clarify, a source device generates an audio signal( line in, PCM (pulse code modulation = wav uncompressed audio), that might then get processed (eg volume control, master, headphone), and then sent to a destination (often an output device like a speaker connector or headphone jack). Because a typical soundcard has an internal hardware mixer, it can usually mix together various inputs (sources) like CD input, mic input and recorded audio signals, and produce a single output signal (mostly in stereo=2 channels). When mixing together externally received signals, no main CPU processing power is used, unless you are trying to record to hard disk etc. 2. gives me two choices and 3., 4., 5. gives me only Master. Which should I choose and why? capture means recording - usually from a line in (eg from a vcr or mp3 player etc), or from a microphone. So exclude those from your choice. If I should be using HDA NVida (Alsa-mixer), why do I have PulseAudio options? Consider pulse audio to be a real-time digital mixer and volume control, where the audio calculations are performed inside your main CPU. In the default setup, once pulseaudio has done it's processing, it passes the result to the alsa driver which outputs the audio data to the soundcard. The soundcard turns the digital audio data into analog audio signals for use with amplifier, speakers, or headphones. Pulseaudio also has enhanced capabilities like remembering that when you playback with xmms that you like to output via your amplifiers and speakers, but when you are viewing a flash video, to playback into your headphones instead, at a different level. Another capability let's you choose the destination playback device while the material is actually being played. A third capability let's the output go to an audio device on another machine. Obviously, this is a bit trickier to set up. ... These individual mixer input controls should normally be left off if you never use them, as they can each introduce noise (hiss, beeps and burbles, etc.) to the system. I will turn them off except for Master and Front. I will experiment with PC Speaker. Of course these are only available to me if I use the default alsa mixer setting. It's not a one or other setting, both parts will still be involved; pulseaudio will process, mix, and attenuate sound signals, whereas alsa will drive the physical hardware. The setting you are seeing lets you decide whether to control the physical driver volume levels or the software generated pulseaudio volume controls. If you mute or turn the alsa master way down, it wont matter how high you turn the pulseaudio mixer, since the alsamixer comes after the pulseaudio one in the audio chain. (also true for the reverse). If you play back a loud audio file, and turn both the pulseaudio source and master up full. Then change to the alsa setting. You can then use the also setting to set up an absolute maximum level that you would want to hear, by adjusting the master. Then you could go back to the pulseaudio setting to adjust the playback to a comfortable setting, and from then on only use the pulseaudio setting. ... * How is sound related to video ? Sound is the sound, video is the picture... The question is too vague to be answerable. In digital format, sound and vision are both represented with digital 1's and 0's. With all video and audio file types, there is a packing together of the audio and video information into the one file. The multiplexed file provides information about when to playback each frame of video in relation to the audio in the file. For example, an mpeg2 (dvd) file might have two frames of video, then 2 of audio, then 1 of video, two audio in an order to achieve a consistent throughput of audio and video data. * Why are there so many files associated with producing sound? In digital audio, the most basic file type is waveform (.wav), where each momentary value of audio is stored, on a 1 for 1 basis. Experiments and calculations can show us that for something we store as quality musical recording we need to
Re: Advice to an audiophobe ??
On Fri, 2008-12-26 at 01:04 +1100, David Timms wrote: William Case wrote: On Wed, 2008-12-24 at 08:30 +1030, Tim wrote: On Tue, 2008-12-23 at 10:55 -0500, William Case wrote: ... 1. Gives me a whole range of adjustments for different channels. (I assume channels means different sources e.g. Master, Headphone, PCM etc.). Just to clarify, a source device generates an audio signal( line in, PCM (pulse code modulation = wav uncompressed audio), that might then get processed (eg volume control, master, headphone), and then sent to a destination (often an output device like a speaker connector or headphone jack). Because a typical soundcard has an internal hardware mixer, it can usually mix together various inputs (sources) like CD input, mic input and recorded audio signals, and produce a single output signal (mostly in stereo=2 channels). When mixing together externally received signals, no main CPU processing power is used, unless you are trying to record to hard disk etc. 2. gives me two choices and 3., 4., 5. gives me only Master. Which should I choose and why? capture means recording - usually from a line in (eg from a vcr or mp3 player etc), or from a microphone. So exclude those from your choice. If I should be using HDA NVida (Alsa-mixer), why do I have PulseAudio options? Consider pulse audio to be a real-time digital mixer and volume control, where the audio calculations are performed inside your main CPU. In the default setup, once pulseaudio has done it's processing, it passes the result to the alsa driver which outputs the audio data to the soundcard. The soundcard turns the digital audio data into analog audio signals for use with amplifier, speakers, or headphones. Pulseaudio also has enhanced capabilities like remembering that when you playback with xmms that you like to output via your amplifiers and speakers, but when you are viewing a flash video, to playback into your headphones instead, at a different level. Another capability let's you choose the destination playback device while the material is actually being played. A third capability let's the output go to an audio device on another machine. Obviously, this is a bit trickier to set up. ... These individual mixer input controls should normally be left off if you never use them, as they can each introduce noise (hiss, beeps and burbles, etc.) to the system. I will turn them off except for Master and Front. I will experiment with PC Speaker. Of course these are only available to me if I use the default alsa mixer setting. It's not a one or other setting, both parts will still be involved; pulseaudio will process, mix, and attenuate sound signals, whereas alsa will drive the physical hardware. The setting you are seeing lets you decide whether to control the physical driver volume levels or the software generated pulseaudio volume controls. If you mute or turn the alsa master way down, it wont matter how high you turn the pulseaudio mixer, since the alsamixer comes after the pulseaudio one in the audio chain. (also true for the reverse). If you play back a loud audio file, and turn both the pulseaudio source and master up full. Then change to the alsa setting. You can then use the also setting to set up an absolute maximum level that you would want to hear, by adjusting the master. Then you could go back to the pulseaudio setting to adjust the playback to a comfortable setting, and from then on only use the pulseaudio setting. ... * How is sound related to video ? Sound is the sound, video is the picture... The question is too vague to be answerable. In digital format, sound and vision are both represented with digital 1's and 0's. With all video and audio file types, there is a packing together of the audio and video information into the one file. The multiplexed file provides information about when to playback each frame of video in relation to the audio in the file. For example, an mpeg2 (dvd) file might have two frames of video, then 2 of audio, then 1 of video, two audio in an order to achieve a consistent throughput of audio and video data. * Why are there so many files associated with producing sound? In digital audio, the most basic file type is waveform (.wav), where each momentary value of audio is stored, on a 1 for 1 basis. Experiments and calculations can show us that for something we store as quality musical recording we need to sample that momentary value at 44kHz (times per second) or higher so as not to disrupt our digital recording with audio aliases. Since we also seem to enjoy the spatial enhancement produced by stereo or more channels, the file needs to store both left and right information. Finally, we found that if we only store the digital value using a small no of bits per sample, when played back we hear a harsh, chunky
Re: Advice to an audiophobe ??
William Case wrote: David, Thank you; If you cut and pasted these answers, I would love to know where (or what site) you got them. If you took the time to write them off the top of your head, I doubly thank you. You have given me enough information to do some proper research of my own particular questions and do a small write up for my own use. Unfortunately the background digital audio theory comes straight from my electronics and communication engineering degree course (15 years ago), but I guess became common knowledge to me due to interest and continued usage, both for at home and work (where we use audio DSP black boxes to save on needing to supply separate audio mixers, equalizers, volume controls, and audio routing boxes to client jobs). If you are into guitar, you might like to try a program like rakarrack. This provides audio processing functionality similar to what those DSP boxes can do, without the expense; but it does require a pretty decent CPU, and an understanding of the jack audio connection kit. While I was expanding on Tim's answer's, I found myself starting to spout technical terms; I just backpedalled each time and tried to find non-technical words to describe the way things are. In terms of audio apps in fedora, my summarizing way over-simplifies things, but hopefully it gives a good idea of the makeup of the system. ( http://www.linux.com/feature/119926 http://en.wikipedia.org/wiki/PulseAudio flowchart a few screens down http://0pointer.de/blog/projects/guide-to-sound-apis.html for a what sound system fits best where) Thanks for the complement, David T. -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: Advice to an audiophobe ??
Thanks Tim; Some of these questions were meant simply as examples of the kind of thing I don't understand. Nonetheless, to flesh them out: On Wed, 2008-12-24 at 08:30 +1030, Tim wrote: On Tue, 2008-12-23 at 10:55 -0500, William Case wrote: * What is the difference between alsa and pulseaudio? Major differences: Pulseaudio can produce different sounds at the same time (e.g. your IM program can bleep at you while your music program carries on playing music, and do so without crashes, hangs, hold-ups for one to finish, or nasty noises), and with individual volume controls for each (e.g. your IM bleeps subdued, while your music may be reasonably loud). That begs the question, when I use the volume control gui the Device: field gives me five options: 1. HDA NVida (Alsa-mixer) 2. Analog Devices AD1986A (OSS Mixer) 3. Playback: HDA Nvida - AD198X Analog (PulseAudio Mixer) 4. Capture: Monitor of HDA NVidia - AD198x (PulseAudio Mixer) 5. Capture: HDA NVidia - AD198x Analog (PulseAudio Mixer) HDA NVida (Alsa-mixer) seems to be the default. 1. Gives me a whole range of adjustments for different channels. (I assume channels means different sources e.g. Master, Headphone, PCM etc.). 2. gives me two choices and 3., 4., 5. gives me only Master. Which should I choose and why? Help is less than useless. There should be a man page but damned if I can find anything helpful. man pulseaudio has techish for installing and setting up the backend but nothing that might be useful to an audio newbie. In case it helps: ]$ lspci returns 00:10.1 Audio device: nVidia Corporation MCP51 High Definition Audio (rev a2) on a ASUS M2NPV-VM motherboard; Fedora 10, Linux kernel 2.6.27.7-134.fc10.x86_64. If I should be using HDA NVida (Alsa-mixer), why do I have PulseAudio options? * What is the difference between Master, PCM, Front, Line-in, CD, PC-Speaker etc. ? Master is the overall volume control over everything, the same control that you're used to on your stereo system. PCM is just the volume control for generated sounds (Waves, MP3s, etc.). Front is the volume control for the front speakers, if you have a system with front and rear speakers (3 - 5, or more, speaker systems). Used as a balance control between front versus rear sound levels. Line-in will control the volume from the analogue audio line-in in socket (which may accept signals from something like 0.2 to 2 volts of audio, compare that to microphone sockets, which may use something in the range of 0.0001 to 0.010 volts, i.e. there's a large factor of difference between line and microphone signal levels). CD will (generally) control the volume from the (3 or 4 pin) analogue audio cable between the CD/DVD drive and the sound card. Although it's *possible* that systems digitally decoding the audio stream from the data from the drive (down the IDE/SATA cable) may *also* pay attention to that volume control, it's generally a hardware control of the line input on the audio card. PC speaker controls, if it's connected, the motherboard beeper volume through the sound card. On some systems, that's a cable between the beeper output and a sound card input, on others its handled without additional cabling, and others it can't be done. These individual mixer input controls should normally be left off if you never use them, as they can each introduce noise (hiss, beeps and burbles, etc.) to the system. I will turn them off except for Master and Front. I will experiment with PC Speaker. Of course these are only available to me if I use the default alsa mixer setting. By the way, I have a Multimedia Systems Selector frontend which gives various perms and combs which don't make sense given the above remarks and which 'help' says to leave alone if you are not an advanced user which, obviously, I am not. The test beep seems to work on just about any combination. There is also a sound preferences gui that is set to autodetect that seems to also test out with any setting giving a long bp. It is all very confusing. And when you do use them, it's dependent on the card whether the nominal position for the level control is all the way up (for simplicity's sake), or part way up (allowing you to listen to signals that are really too low in level). And again, there's variances as to where the partial position may be (e.g. half way, or three quarters up). Also, what's connected to the mixer plays a role there, whether it has a low output level that will need boosting, the same level as the card expects, or a high level that will normally be too much. * How is sound related to video ? Sound is the sound, video is the picture... The question is too vague to be answerable. Sorry, I didn't mean to be vague. Most of my sound problems over the years seem to have been related to sound that goes with video of different kinds - Flash being the most
Advice to an audiophobe ??
Hi; I have avoided sound technology most of my life. I have a 'tin ear' and most music just sounds to me like somebody talking in an annoying voice. However, recent problems with alsa mixer and/or pulseaudio has convinced me that the time has come to spend some time learning the rudiments of sound technology. So ... Can someone recommend a site or manual that explains things like: * What is the difference between alsa and pulseaudio? * Which should I choose for the Device: field? * What is the difference between Master, PCM, Front, Line-in, CD, PC-Speaker etc. ? * How is sound related to video ? * Why are there so many files associated with producing sound? * Etc., etc., etc.? ? I have googled, searched Wikipedia, read the PulseAudio documentation as well as Gnome Help. It all still leaves me befuddled -- either too simple or two technical. Once I try to throw in the concept of various 'codecs' I am lost. I am not asking for a personal explanation of the above questions (I have a bunch more) but all learning suggestions gratefully received. -- Regards Bill Fedora 10, Gnome 2.24.2 Evo.2.24.2, Emacs 22.2.1 -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
Re: Advice to an audiophobe ??
On Tue, 2008-12-23 at 10:55 -0500, William Case wrote: * What is the difference between alsa and pulseaudio? Major differences: Pulseaudio can produce different sounds at the same time (e.g. your IM program can bleep at you while your music program carries on playing music, and do so without crashes, hangs, hold-ups for one to finish, or nasty noises), and with individual volume controls for each (e.g. your IM bleeps subdued, while your music may be reasonably loud). * What is the difference between Master, PCM, Front, Line-in, CD, PC-Speaker etc. ? Master is the overall volume control over everything, the same control that you're used to on your stereo system. PCM is just the volume control for generated sounds (Waves, MP3s, etc.). Front is the volume control for the front speakers, if you have a system with front and rear speakers (3 - 5, or more, speaker systems). Used as a balance control between front versus rear sound levels. Line-in will control the volume from the analogue audio line-in in socket (which may accept signals from something like 0.2 to 2 volts of audio, compare that to microphone sockets, which may use something in the range of 0.0001 to 0.010 volts, i.e. there's a large factor of difference between line and microphone signal levels). CD will (generally) control the volume from the (3 or 4 pin) analogue audio cable between the CD/DVD drive and the sound card. Although it's *possible* that systems digitally decoding the audio stream from the data from the drive (down the IDE/SATA cable) may *also* pay attention to that volume control, it's generally a hardware control of the line input on the audio card. PC speaker controls, if it's connected, the motherboard beeper volume through the sound card. On some systems, that's a cable between the beeper output and a sound card input, on others its handled without additional cabling, and others it can't be done. These individual mixer input controls should normally be left off if you never use them, as they can each introduce noise (hiss, beeps and burbles, etc.) to the system. And when you do use them, it's dependent on the card whether the nominal position for the level control is all the way up (for simplicity's sake), or part way up (allowing you to listen to signals that are really too low in level). And again, there's variances as to where the partial position may be (e.g. half way, or three quarters up). Also, what's connected to the mixer plays a role there, whether it has a low output level that will need boosting, the same level as the card expects, or a high level that will normally be too much. * How is sound related to video ? Sound is the sound, video is the picture... The question is too vague to be answerable. * Why are there so many files associated with producing sound? Driver-wise, there's a plethora of different sound cards, which all work very differently, and each have differing controls available to the user. There's a plethora of different audio codecs. For playing MIDI files, something needs to generate the actual sounds each note will play (that could be one file per sound, or you could make use of hardware that does it). That's another almost unanswerable question. -- [...@localhost ~]$ uname -r 2.6.27.7-53.fc9.i686 Don't send private replies to my address, the mailbox is ignored. I read messages from the public lists. -- fedora-list mailing list fedora-list@redhat.com To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list Guidelines: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines
