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<h1><a class="anchor" name="sample">Sample Format Specifications </a></h1><h2><a class="anchor" name="overv_sec">
Overview</a></h2>
PulseAudio is capable of handling a multitude of sample formats, rates and channels, transparently converting and mixing them as needed.<h2><a class="anchor" name="format_sec">
Sample Format</a></h2>
PulseAudio supports the following sample formats:<p>
<ul>
<li>PA_SAMPLE_U8 - Unsigned 8 bit integer PCM. </li>
<li>PA_SAMPLE_S16LE - Signed 16 integer bit PCM, little endian. </li>
<li>PA_SAMPLE_S16BE - Signed 16 integer bit PCM, big endian. </li>
<li>PA_SAMPLE_FLOAT32LE - 32 bit IEEE floating point PCM, little endian. </li>
<li>PA_SAMPLE_FLOAT32BE - 32 bit IEEE floating point PCM, big endian. </li>
<li>PA_SAMPLE_ALAW - 8 bit a-Law. </li>
<li>PA_SAMPLE_ULAW - 8 bit mu-Law. </li>
<li>PA_SAMPLE_S32LE - Signed 32 bit integer PCM, little endian. </li>
<li>PA_SAMPLE_S32BE - Signed 32 bit integer PCM, big endian.</li>
</ul>
The floating point sample formats have the range from -1 to 1.<p>
The sample formats that are sensitive to endianness have convenience macros for native endian (NE), and reverse endian (RE).<h2><a class="anchor" name="rate_sec">
Sample Rates</a></h2>
PulseAudio supports any sample rate between 1 Hz and 4 GHz. There is no point trying to exceed the sample rate of the output device though as the signal will only get downsampled, consuming CPU on the machine running the server.<h2><a class="anchor" name="chan_sec">
Channels</a></h2>
PulseAudio supports up to 16 individiual channels. The order of the channels is up to the application, but they must be continous. To map channels to speakers, see <a class="el" href="channelmap.html">Channel Maps</a>.<h2><a class="anchor" name="calc_sec">
Calculations</a></h2>
The PulseAudio library contains a number of convenience functions to do calculations on sample formats:<p>
<ul>
<li><a class="el" href="sample_8h.html#674c3449416e97b71a75feb64ca59ad4" title="Return the amount of bytes playback of a second of audio with the specified sample...">pa_bytes_per_second()</a> - The number of bytes one second of audio will take given a sample format. </li>
<li><a class="el" href="sample_8h.html#035d79171e183f6315e6e65436f5e939" title="Return the size of a frame with the specific sample type.">pa_frame_size()</a> - The size, in bytes, of one frame (i.e. one set of samples, one for each channel). </li>
<li><a class="el" href="sample_8h.html#ae286d84c2975248f65f804d4c24ef39" title="Return the size of a sample with the specific sample type.">pa_sample_size()</a> - The size, in bytes, of one sample. </li>
<li><a class="el" href="sample_8h.html#b3c5f4af357686fdc7df46c9581154bd" title="Calculate the time the specified bytes take to play with the specified sample type...">pa_bytes_to_usec()</a> - Calculate the time it would take to play a buffer of a certain size.</li>
</ul>
<h2><a class="anchor" name="util_sec">
Convenience Functions</a></h2>
The library also contains a couple of other convenience functions:<p>
<ul>
<li><a class="el" href="sample_8h.html#0d9ad972ee71ef6bff8aaafd44fdb229" title="Return non-zero when the sample type specification is valid.">pa_sample_spec_valid()</a> - Tests if a sample format specification is valid. </li>
<li><a class="el" href="sample_8h.html#c4c2262bf88bd90fc68767e69fb6810c" title="Return non-zero when the two sample type specifications match.">pa_sample_spec_equal()</a> - Tests if the sample format specifications are identical. </li>
<li><a class="el" href="sample_8h.html#70804b50d5507f9a7680d4e809e337ed" title="Return a descriptive string for the specified sample format.">pa_sample_format_to_string()</a> - Return a textual description of a sample format. </li>
<li><a class="el" href="sample_8h.html#2819db448dd45edb5d777b7568dd3236" title="Parse a sample format text.">pa_parse_sample_format()</a> - Parse a text string into a sample format. </li>
<li><a class="el" href="sample_8h.html#3dd4815bbd51d5467b40e28d05ad948d" title="Pretty print a sample type specification to a string.">pa_sample_spec_snprint()</a> - Create a textual description of a complete sample format specification. </li>
<li><a class="el" href="sample_8h.html#4992ec70d79de601c6f8f6cc5cab8e59" title="Pretty print a byte size value.">pa_bytes_snprint()</a> - Pretty print a byte value (e.g. 2.5 MiB). </li>
</ul>
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