VCRadio (9)


Tuner Hacks

Hackaday has a brilliant series of posts on hacking TV tuners. Check these out:

Related Posts:




MP3 Patent Countdown

Various Sagebrush programs are able to record and play MP3, but only if you already have an ACM MP3 audio codec installed on your computer, which was common during Windows XP but less  likely in later versions of Windows. We do not bundle an MP3 encoder with our products because the technology is covered by software patents, whose validity is recognized in the country where Sagebrush is located. The licensing fees are prohibitive.

When do the patents covering MP3 encoding and decoding actually expire in the USA? That is complicated, as issues relating to software patents tend to be. Tunequest provides a handy list of patents, with the last expiring December 30, 2017. The Wikipedia article on MP3 raises the question of validity of the later patents:

The various MP3-related patents expire on dates ranging from 2007 to 2017 in the U.S.[52] The initial near-complete MPEG-1 standard (parts 1, 2 and 3) was publicly available on December 6, 1991 as ISO CD 11172.[53][54] In the United States, patents cannot claim inventions that were already publicly disclosed more than a year prior to the filing date, but for patents filed prior to June 8, 1995, submarine patents made it possible to extend the effective lifetime of a patent through application extensions. Patents filed for anything disclosed in ISO CD 11172 a year or more after its publication are questionable; if only the known MP3 patents filed by December 1992 are considered, then MP3 decoding may be patent free in the US by September 2015 when U.S. Patent 5,812,672 expires which had a PCT filing in Oct 1992.[55][56][57]

Just for the sake of caution, let us take the more conservative date of December 30, 2017.

[ujicountdown id=”mp3patent” expire=”2017/30 23:59″]

(We are not lawyers, and nothing in this article should be taken as legal advice.)

We hope and expect to be supporting RecAll and RecAll-PRO well into the next decade, so it is quite possible to wait out this particular portfolio of patents.

Related Posts:

 




Anniversary of Betamax Decision

January 17, 1984 the US Supreme Court decided the case of Sony Corporation of America et al. v. Universal City Studios, Inc., et al., reaffirming that home use recording is considered fair use, and manufacturers were not liable for contributory infringement.

[youtube=http://www.youtube.com/watch?v=BqxqYiptNe0]




USB Tuner Support for Vista

  • November 19, 2007
  • VCRadio

VCRadio version 1.9 has been stuck in beta for several months. Here’s why:

We have acquired several USB TV/FM tuners to support this product, and none of them have drivers running under Vista yet! We really don’t want to purchase another USB NTSC/FM tuner if we don’t have to, but it might be necessary to test with Vista. We do have several non-TV tuners working with Vista, but for completeness we wanted to look at TV tuners as well.

Does any other VCRadio user have a USB TV/FM tuner with drivers updated for Vista?




High Def Radio Startup

NPR Morning Edition has a story about a couple starting a business to produce high definition radios and the difficulties encountered bringing it to market.
(link)

(Our company looked briefly at venturing into the hardware world by designing our own HD Radio device, but were scared away by threats of a broadcast flag.)




Radio How?

The respected Secret Life of Machines TV series explains the inner workings of radio:

Part 1
Part 2
Part 3

[youtube=http://www.youtube.com/watch?v=3ehVVpY6XE4]




Example FM Tuner Design II

In a previous post we pointed to a design project report for a USB FM tuner . Here is another tuner project, a reference design by a semiconductor company wishing to promote its FM tuner ICs. The application note includes software, firmware, board layout, and parts list.

The reference design kit is available for purchase through Digi-Key. We are not able to link directly to the product page for this item, but search for part number “336-1293-ND”.

We will be able to include support for this tuner in VCRadio if anyone requests.




Convert WAV to MP3

I accidentally recorded a few audio files in .WAV file format instead of MP3. Is there an easy way to convert?

If the .WAV file was recorded using MPEG compression, simply rename the file to use an .MP3 file extension, and the file will play in the vast majority of MP3 player programs and MP3 devices.

Why does this work?

MP3 was designed to be a streaming format, and part of that design is to deliver the audio data in sections (called frames) and have a way to synch up to the next frame in case of loss of data, network problems, or starting playback in the middle of a stream. MP3 files often include non-audio data, called tags, at the beginning or end of the file, and player software is already designed to skip over tags to find the beginning of the first frame of audio.

Here is a conceptual schematic of one MP3 file with no tags:

[mp3 frame]
[mp3 frame]
[mp3 frame]

The WAV file format has a few extra bytes at the beginning of the file, but MP3 players will usually ignore bytes at the beginning of a file they don’t understand. Refer to this conceptual schematic of one WAV file:

‘RIFF’ [4 length bytes]
‘WAVE’
‘ fmt’ [4 length bytes]
‘data’ [4 length bytes]
[mp3 frame]
[mp3 frame]
[mp3 frame]

My WAV file does not use MPEG compression. Now what do I do?

Read rest of tutorial here.




Example USB FM Tuner Design

For persons interested in designing and constructing their own computer-controlled radio tuner, or those just curious about design issues, check out this college design project report, with more documents here.