Jonathan_Huang@compal.com
2003-Oct-06 19:30 UTC
[vorbis-dev] hlp: off topic but need experty---How to calculate amplitute of l eaner pcm data
To vorbis expert group: Sorry to drop this message but I need help :-( I got the linear pcm data from windows waveio api or vorbis codec. I think the data is signed. My goal is to construct a db scale(ppm) to display the volume while playing just like the old tape deck. The original amplitude is expressed in turn of voltage. I have no idea how to coverted it in digital form. I saw a formula like p= 1/n * sum(x=0 to n) (pcmvalue/2 to power of (num of bits))^2 and signal level L=10 log p + C. I also noted I need to add a constant for a or mu law coded pcm. Do I need to add any for linear pcm? How do I convert this to peak power meter or this is it? Please let me know if there is a place I can ask or find more relative data. John -----Original Message----- From: Anna_Zhavor@abbyy.com [mailto:Anna_Zhavor@abbyy.com] Sent: Monday, October 06, 2003 7:52 PM To: vorbis-dev@xiph.org Subject: [vorbis-dev] Question about distribution Vorbis software Dear Sirs, we should like to use your software for compression our sound files. We use the following dlls: ogg.dll, vorbis.dll, vorbisenc.dll, vorbisfile.dll We will insert your copyright "Copyright (c) 2003, Xiph.org Foundation" in the documentations of our software and the following text in our End-User License Agreement: "THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE." Is it enough? Thank you, Anna Zhavoronkova, Lingvo product manager, ABBYY Software --- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-dev-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered. <p><p>--- >8 ---- List archives: http://www.xiph.org/archives/ Ogg project homepage: http://www.xiph.org/ogg/ To unsubscribe from this list, send a message to 'vorbis-dev-request@xiph.org' containing only the word 'unsubscribe' in the body. No subject is needed. Unsubscribe messages sent to the list will be ignored/filtered.