Hi, Many thanks for your answer. Please see my comments below. Thanks. -----Original Message----- From: Clemens Ladisch [mailto:cladisch@xxxxxxxxxxxx] Sent: Thursday, October 19, 2006 10:55 AM To: Assaf Hoffman; alsa-devel@xxxxxxxxxxxxxxxxxxxxx Cc: Rita Shtern Subject: Re: Question on PCM formats Assaf Hoffman wrote: > I was looking in http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html > and I have some questions regarding the PCM format paragraph: > > Q1: I think the sentence: > "...but the sample is stored in low three bits." > Should be > "...but the sample is stored in low three bytes." Yes, thanks. > Q2: What is the meaning of "full range" in the sentence: > "Some hardware does not support processing of full range"? In that case, "full range" is the size of the samples as specified by the sample format (in the example, 32 bits). [Assaf]: If you could give some examples there it would be great. > Q3: I'm working with kernel 2.6.12.6 and I could not find the > snd_pcm_hw_params_get_sbits() function there. In which kernel version > can I find it? This function is part of ALSA's user space API. It just returns the value of the kernel's msbits field. [Assaf]: What is the msbits fields? How the kernel get that information? Can you point me to where I can get an ALSA user space code that will demonstrate how to use the snd_pcm_hw_params_get_sbits()? > Q4: Working with 2.6.12.6 kernel, how can I solve the problem of the > ICE1712? How do I tell the stack where is the sound sample bit start > inside the 32-bit frame? When the number of valid bits (_get_sbits()) is not as large as the number of bits of the sample format, the valid bits are always the most significant bits. This means that applications can just ignore the _get_sbits() function and pretend that the ICE1712 uses 32-bit samples. [Assaf]: Regarding the first sentence in the above paragraph, isn't the "number of valid bits" and the "number of bits in sample" are the same thing? Can you elaborate? There are special sample formats for hardware that aligns its data in the least significant bits of a word, e.g., S24_xE is for 24-bit samples in the lower three bytes of a 32-bit word. [Assaf]: What about x20_3xE format? Where the 20-bit sample is located in the 24-bit memory? HTH Clemens ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
