- <title>Using VLC to stream bittorrent sources</title>
- <link>http://people.skolelinux.org/pere/blog/Using_VLC_to_stream_bittorrent_sources.html</link>
- <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Using_VLC_to_stream_bittorrent_sources.html</guid>
- <pubDate>Wed, 14 Feb 2018 08:00:00 +0100</pubDate>
- <description><p>A few days ago, a new major version of
-<a href="https://www.videolan.org/">VLC</a> was announced, and I
-decided to check out if it now supported streaming over
-<a href="http://bittorrent.org/">bittorrent</a> and
-<a href="https://webtorrent.io">webtorrent</a>. Bittorrent is one of
-the most efficient ways to distribute large files on the Internet, and
-Webtorrent is a variant of Bittorrent using
-<a href="https://webrtc.org">WebRTC</a> as its transport channel,
-allowing web pages to stream and share files using the same technique.
-The network protocols are similar but not identical, so a client
-supporting one of them can not talk to a client supporting the other.
-I was a bit surprised with what I discovered when I started to look.
-Looking at
-<a href="https://www.videolan.org/vlc/releases/3.0.0.html">the release
-notes</a> did not help answering this question, so I started searching
-the web. I found several news articles from 2013, most of them
-tracing the news from Torrentfreak
-("<a href=https://torrentfreak.com/open-source-giant-vlc-mulls-bittorrent-support-130211/">Open
-Source Giant VLC Mulls BitTorrent Streaming Support</a>"), about a
-initiative to pay someone to create a VLC patch for bittorrent
-support. To figure out what happend with this initiative, I headed
-over to the #videolan IRC channel and asked if there were some bug or
-feature request tickets tracking such feature. I got an answer from
-lead developer Jean-Babtiste Kempf, telling me that there was a patch
-but neither he nor anyone else knew where it was. So I searched a bit
-more, and came across an independent
-<a href="https://github.com/johang/vlc-bittorrent">VLC plugin to add
-bittorrent support</a>, created by Johan Gunnarsson in 2016/2017.
-Again according to Jean-Babtiste, this is not the patch he was talking
-about.</p>
-
-<p>Anyway, to test the plugin, I made a working Debian package from
-the git repository, with some modifications. After installing this
-package, I could stream videos from
-<a href="https://www.archive.org/">The Internet Archive</a> using VLC
-commands like this:</p>
-
-<p><blockquote><pre>
-vlc https://archive.org/download/LoveNest/LoveNest_archive.torrent
-</pre></blockquote></p>
-
-<p>The plugin is supposed to handle magnet links too, but since The
-Internet Archive do not have magnet links and I did not want to spend
-time tracking down another source, I have not tested it. It can take
-quite a while before the video start playing without any indication of
-what is going on from VLC. It took 10-20 seconds when I measured it.
-Some times the plugin seem unable to find the correct video file to
-play, and show the metadata XML file name in the VLC status line. I
-have no idea why.</p>
-
-<p>I have created a <a href="https://bugs.debian.org/890360">request for
-a new package in Debian (RFP)</a> and
-<a href="https://github.com/johang/vlc-bittorrent/issues/1">asked if
-the upstream author is willing to help make this happen</a>. Now we
-wait to see what come out of this. I do not want to maintain a
-package that is not maintained upstream, nor do I really have time to
-maintain more packages myself, so I might leave it at this. But I
-really hope someone step up to do the packaging, and hope upstream is
-still maintaining the source. If you want to help, please update the
-RFP request or the upstream issue.</p>
-
-<p>I have not found any traces of webtorrent support for VLC.</p>
+ <title>Measuring the speaker frequency response using the AUDMES free software GUI - nice free software</title>
+ <link>http://people.skolelinux.org/pere/blog/Measuring_the_speaker_frequency_response_using_the_AUDMES_free_software_GUI___nice_free_software.html</link>
+ <guid isPermaLink="true">http://people.skolelinux.org/pere/blog/Measuring_the_speaker_frequency_response_using_the_AUDMES_free_software_GUI___nice_free_software.html</guid>
+ <pubDate>Mon, 22 Oct 2018 08:40:00 +0200</pubDate>
+ <description><p><img src="http://people.skolelinux.org/pere/blog/images/2018-10-22-audmes-measure-speakers.png" align="right" width="40%"/></p>
+
+<p>My current home stereo is a patchwork of various pieces I got on
+flee markeds over the years. It is amazing what kind of equipment
+show up there. I've been wondering for a while if it was possible to
+measure how well this equipment is working together, and decided to
+see how far I could get using free software. After trawling the web I
+came across an article from DIY Audio and Video on
+<a href="https://www.diyaudioandvideo.com/Tutorial/SpeakerResponseTesting/">Speaker
+Testing and Analysis</a> describing how to test speakers, and it listing
+several software options, among them
+<a href="https://sourceforge.net/projects/audmes/">AUDio MEasurement
+System (AUDMES)</a>. It is the only free software system I could find
+focusing on measuring speakers and audio frequency response. In the
+process I also found an interesting article from NOVO on
+<a href="http://novo.press/understanding-speaker-specifications-and-frequency-response/">Understanding
+Speaker Specifications and Frequency Response</a> and an article from
+ecoustics on
+<a href="https://www.ecoustics.com/articles/understanding-speaker-frequency-response/">Understanding
+Speaker Frequency Response</a>, with a lot of information on what to
+look for and how to interpret the graphs. Armed with this knowledge,
+I set out to measure the state of my speakers.</p>
+
+<p>The first hurdle was that AUDMES hadn't seen a commit for 10 years
+and did not build with current compilers and libraries. I got in
+touch with its author, who no longer was spending time on the program
+but gave me write access to the subversion repository on Sourceforge.
+The end result is that now the code build on Linux and is capable of
+saving and loading the collected frequency response data in CSV
+format. The application is quite nice and flexible, and I was able to
+select the input and output audio interfaces independently. This made
+it possible to use a USB mixer as the input source, while sending
+output via my laptop headphone connection. I lacked the hardware and
+cabling to figure out a different way to get independent cabling to
+speakers and microphone.</p>
+
+<p>Using this setup I could see how a large range of high frequencies
+apparently were not making it out of my speakers. The picture show
+the frequency response measurement of one of the speakers. Note the
+frequency lines seem to be slightly misaligned, compared to the CSV
+output from the program. I can not hear several of these are high
+frequencies, according to measurement from
+<a href="http://freehearingtestsoftware.com">Free Hearing Test
+Software</a>, an freeware system to measure your hearing (still
+looking for a free software alternative), so I do not know if they are
+coming out out the speakers. I thus do not quite know how to figure
+out if the missing frequencies is a problem with the microphone, the
+amplifier or the speakers, but I managed to rule out the audio card in my
+PC by measuring my Bose noise canceling headset using its own
+microphone. This setup was able to see the high frequency tones, so
+the problem with my stereo had to be in the amplifier or speakers.</p>
+
+<p>Anyway, to try to role out one factor I ended up picking up a new
+set of speakers at a flee marked, and these work a lot better than the
+old speakers, so I guess the microphone and amplifier is OK. If you
+need to measure your own speakers, check out AUDMES. If more people
+get involved, perhaps the project could become good enough to
+<a href="https://bugs.debian.org/910876">include in Debian</a>? And if
+you know of some other free software to measure speakers and amplifier
+performance, please let me know. I am aware of the freeware option
+<a href="https://www.roomeqwizard.com/">REW</a>, but I want something
+that can be developed also when the vendor looses interest.</p>