Hitchhiker's Guide to Openbsd

Why am I not getting the writing speed I expected?
Instead of the above writing output, you may see something like: 
4784128/1545832448 ( 0.3%) @0.7x, remaining 26:50
7929856/1545832448 ( 0.5%) @0.7x, remaining 29:05
14123008/1545832448 ( 0.9%) @0.7x, remaining 27:06
...
which is much slower. It means you are somehow not getting enough throughput on whatever bus your 
DVD writer is using. In the above example, the USB DVD writer was attached to a machine on which 
the 
ehci(4)
driver, used by USB 2.0 controllers, failed to initialize properly. As always, you are welcome 
to provide patches and test results. The DVD writer fell back to the slower USB 1.1 interface, which 
causes reduced throughput. Indeed, USB 1.1 is limited to 12 Mbit/s, which amounts to 1.43 MB/s or 
1.08x in DVD speed terms. The DVD writer falls back to a lower pace than the maximum, to reduce the 
risk of buffer underruns. 
13.11 - But I want my media files in format FOO.
Converting between different audio formats
Let's say we want to process the sound recording from 
FAQ 13 - Audio Recording
. This recording has 
been stored in the raw format. It will be useful to convert it, because the raw format does not include 
headers and the recording parameters will need to be specified at every usage of the file. 
One sound conversion tool is 
audio/sox
, available through packages and ports. sox supports AIFF, 
AU, MP3, Ogg Vorbis, RIFF WAV and raw formats, as well as some of the more exotic audio formats 
out there. Below is an example for converting the recording to RIFF WAV format. 
$ sox -U -c 1 -r 8000 -b myvoice.raw myvoice.wav
Note that the specified parameters correspond to the recording parameters specified before the 
http://www.openbsd.org/faq/faq13.html (21 of 25)9/4/2011 10:02:21 AM

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13 - Multimedia
recording. This was just an example. More audio-related libraries and software can be used for audio 
conversion. 
Note: It is not recommended to convert between different lossy compression formats. For instance, the 
MP3 and Vorbis codecs throw away different parts of an original audio waveform. Therefore, when 
converting a MP3 file to Ogg Vorbis, the end result will probably sound worse than the original MP3.