It does not perform any sound playback or recording. What gcc parameters need to be added? (currently using Ubuntu Feisty 7.04) undocumented bs wtf! To let other clients read from them, we have to allow read access and read subscription. Another new function we see here is snd_pcm_avail_update. http://phabletkeyboards.com/error-codes/soap-api-error-codes.php
snd_pcm_avail_update()) are thread-safe and can be called concurrently from multiple threads. The two arguments (in order: SOCKET,PCM) specify UNIX socket name (for example /tmp/alsa.socket) for server communication and server's PCM name. intsnd_pcm_drain (snd_pcm_t *pcm) Stop a PCM preserving pending frames. Any other events (e.g. http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html
when i run the listing1 of this doc it went fine and when i tried to run the second listing it says like this. Note this function does not update the actual r/w pointer for applications. For this reason the function takes a pointer to an unsigned integer, so it can change the value of our rrate variable to reflect the actual rate set.
snd_pcm_writei, snd_pcm_writenThe snd_pcm_writei() and snd_pcm_writen() functions can conditionally start the stream - SND_PCM_STATE_RUNNING. The function is thread-safe when built with the proper option. int snd_pcm_poll_descriptors_revents ( snd_pcm_t * pcm, struct pollfd * pfds, unsigned int nfds, unsigned short * revents ) get returned events from poll descriptors Parameters: pcmPCM handle pfdsarray of poll descriptors Snd_pcm_recover I am using file descriptor of this file insted of 0 (stdin) when I call function read like this: int fd = open( argv , O_RDONLY ); ......
Firstly, this article is really good. Snd_pcm_writei Application developers are encouraged to program using the library API and not the kernel interface. We check the return code for a number of error conditions. http://alsa.opensrc.org/HowTo_Asynchronous_Playback When it is brought to SETUP state, this function automatically calls snd_pcm_prepare() function to bring to the PREPARED state as below.
Simple Sound Playback /* This example reads standard from input and writes to the default PCM device for 5 seconds of data. */ /* Use the newer ALSA API */ #define Snd_pcm_nonblock ALSA transfers There are two methods to transfer samples in application. ALSA Architecture The ALSA API can be broken down into the major interfaces it supports: Control interface: a general-purpose facility for managing registers of sound cards and querying the available devices. More samples are collected to frames (frame is terminology for ALSA) depending on count of converters used at one specific time.
If you already have written an audio application, you may want to add native support for the ALSA sound drivers. http://comphelp.org/guide/snd-pcm-write-error-codes/ Thanks to Frank Neumann for carefully reading this document. Alsa Pcm Example If you would like to vary the tempo, it is convenient to specify the time in ticks. Alsa Error Codes Parameters: pcm1first PCM handle pcm2first PCM handle Returns:0 on success otherwise a negative error code The two PCMs will start/stop/prepare in sync.
It operates much like the kernel write system call, except that the size is specified in frames. check over here Instead, we call snd_seq_ev_set_source to make the event originate from the desired output port. Resources for this article: /article/7705. Parameters: pcmPCM handle Returns:0 on success otherwise a negative error code Return values: -EAGAINresume can't be proceed immediately (audio hardware is probably still suspended) -ENOSYShardware doesn't support this feature This function Snd_pcm_hw_params_set_channels
Fatih CROSS_COMPILE Submitted by rangel (not verified) on Tue, 11/16/2010 - 14:34. where each character represents a byte in the buffer, and padding should of course be ignored (it's just for clarity). \ Note that I emphasized might in the non-interleaved case. This is checked with snd_seq_input_pending, which returns the byte size of the events remaining in the input buffer. his comment is here Does Wi-Fi traffic from one client to another travel via the access point?
Examples: /test/pcm.c. Snd_pcm_wait Psy - http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m.html#g012e8b999070e72ab23514f25e7d6482 clearly says that snd_pcm_avail_update has to be called before writing to the device takes place, in order to update the r/w-pointer. snd_pcm_startThe snd_pcm_start() function enters the SND_PCM_STATE_RUNNING after a successful finish.
SND_PCM_STATE_XRUNThe PCM device reached overrun (capture) or underrun (playback). However, here we do not specify the buffersize, but we set the periodsize instead. try: "strace ./play < sample.raw" or "ldd play" and view if the correct path of library is linking Volume needs to increase Submitted by djguha (not verified) on Sat, 09/18/2010 - Snd_pcm_writei Example For a design that makes producing data in lockstep with the sound driver relatively easy, look at jack (http://jackaudio.org/) which is based on registering a callback function with the sound playback
When I change the sampling frequency value to 48 kHz then I got the error message: unable to set hw parameters: Invalid argument For any other sampling frequency it works ok. Otherwise there will be a buffer overrun. In contrast, OSS/Free drivers are programmed at the kernel system call level and require the developer to specify device filenames and perform many functions using ioctl calls. http://phabletkeyboards.com/error-codes/snd-pcm-readi-error-codes.php The position is not synced with hardware (driver) position in the sound ring buffer in this function.
miniFMsynth always writes chunks of fixed size, so nframes always equals BUFSIZE. Is that how it works? We do this with the macro snd_pcm_hw_params_alloca. This time it works but when i run ./example3 < /dev/urandom this command it gives me veri bad sound like "CCcczzZZZZzzzrrttTtTT".
It happened the same to me. And what exactly is the SND_PCM_ASYNC flag for? intsnd_pcm_unlink (snd_pcm_t *pcm) Remove a PCM from a linked group. int snd_pcm_hw_params ( snd_pcm_t * pcm, snd_pcm_hw_params_t * params ) Install one PCM hardware configuration chosen from a configuration space and snd_pcm_prepare it.
The latency is introduced in several places. The first write access will start the PCM playback. Just try it out. For other operations related to playback or the device structure, again, see the API reference: http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m.html The callback function To prevent buffer under-runs, we need to refill the buffer every so
The strangest thing is, if I give snd_pcm_writei() all the frames, and remove the for-loop, nothing is played. The tempo is passed to snd_seq_queue_tempo_set_tempo in microseconds per tick. Parameters: pcmPCM handle paramsConfiguration container Returns:0 on success otherwise a negative error code The software parameters can be changed at any time. The function is thread-safe when built with the proper option.