Lossless compared with lossy data compression

When i first looked into this i was like wtf? too... but this is all to do with the data compression.

Lossless data compression is a class of data compression algorithms that allows the exact original data to be reconstructed from the compression data. This is the opposite to lossy data compression, which allows an approximation of the original data to be reconstructed, in exchange fore better compressions rates.

What's the advantages?

One advantage of the lossy methods over lossless methods is that in some cases the lossy method can be compressed smaller than its counterpart, importantly while still meeting the requirements of the application.

Lossy methods are most often used by data are intended for human interpretation where the mind can fill in the blanks or see past minor errors. Ideally lossy compression is transparent or imperceptible, otherwise you would notice it sounded bad and not use it. If you do notice an anomaly it is called a compression artifacts.

Audio can be compressed at 10:1 with imperceptible loss of quality. The compression rate in lossy compression is 5-6%, where as in lossless compression it is about 50-60% of the actual file.

Cheers Guys,

Matt Price

List of Lossy Formats (links to wikipedia)
AAC
ADPCM
ATRAC
Dolby AC-3
MP2
MP3
Musepack (based on Musicam)
Ogg Vorbis (noted for its lack of patent restrictions)
WMA

List of Lossless formats (links to wikipedia)
Free Lossless Audio Codec – FLAC
Apple Lossless – ALAC (Apple Lossless Audio Codec)
apt-X – Lossless
Adaptive Transform Acoustic Coding – ATRAC
Audio Lossless Coding – also known as MPEG-4 ALS
MPEG-4 SLS – also known as HD-AAC
Direct Stream Transfer – DST
Dolby TrueHD
DTS-HD Master Audio
Meridian Lossless Packing – MLP
Monkey's Audio – Monkey's Audio APE
OptimFROG
RealPlayer – RealAudio Lossless
Shorten – SHN
TTA – True Audio Lossless
WavPack – WavPack lossless
WMA Lossless – Windows Media Lossless

Sampling theorem

The Nyquist–Shannon sampling theorem, after Harry Nyquist and Claude Shannon, is a fundamental result in the field of information theory, in particular telecommunications and signal processing. Sampling is the process of converting a signal(for example, a function of continuous time or space) into a numeric sequence (a function of discrete time or space).

Sampling theorem which in essence shows that a bandlimited analog signal can be reconstructed perfectly from an infinite sequence of samples if the sample rate exceeds 2B samples per second. B is the highest frequency in the original signal. If the signal contains components at exactly B hertz, then samples spaced 1/(2B) seconds do NOT completely determine the signal.

E.g. 20,000 Hertz into this forumla will not be reconstructed perfectly at anything less than 0.00003 seconds per sample. Recording at a sample rate of 48kHz is sampling at 0.00002 seconds per sample, hence for situations like recording dialogue where the highest frequency for normal conversation is below 20kHz (because we can't hear higher).

Possibly Useful Drawing of a 2hz sine wave

So in recording effects if you wanted to have flexibility to manipulate then you can record at 192kHz and then the spacing is 1 sample every 0.0000052083 of a second, this is useful for slowing down samples more effectively than less samples.

This is again like most perfect theories based on a perfect world and so is an approximate in our not so perfect world.

Hope this ended up making sense.

Thanks,

Matt Price

Ohm ohm ohm... amp?

Ohm's or Ω is the SI or system of international unit of electrical resistance and gets it's name from Georg Simon Ohm. Ohm determined that there is a direct proportionality between the potential difference (voltage) applied across a conductor and the resultant electric current. This relationship is now known as Ohm's law.

So an Ohm is a unit of resistance between two points of a conductor when, for instance, a constant 1 volt difference is applied to each point and it produces 1 ampere.

Ampere  It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics. In practice, its name is often shortened to amp. An amp is a SI for basically a rate of flow in a wire. 

So an ohm is just a way of measuring how easily electricity flows along a certain path. Electrical resistance shares some conceptual parallels with the mechanical notion of friction.

Leave comments if still confused =]

Thanks,

Matt Price

The famous Wilhelm scream

The Wilhelm Scream originates from the film Distant Drums in 1951. The scene in the video below soliders are wading through a swamp and one (Wilhelm) gets bitted and dragged underwater by an aligator, the scream was re-recorded in a single take, along with 5 others. the 4th 5th and 6th are also used earlier in the movie. 4-6 are all recognisable as the Wilhelm scream by many sound editors.

Below is the scene with the original Wilhelm Scream.

Below is a compalation of Wilhelm screams

Hope you enjoyed this,
Thanks,
Matt Price

ADR, dubbing, looping and post sync

All the names in the title mean the same thing roughly. Though you should be aware that you can dub on music to a film. ADR stands for automated dialogue replacement, this is the post production process for replacing the lines, words, sentences of dialogue with a new copy or different lines. 

This is for various reasons which include but are not limited to: Poor recording on set, pops and clicks that can't be cleaned, wrong lines, poor performance and so on... This is usually hell for many directors, actors and crew because it is time consuming and so expensive, coupled with the fact the voice has to match the performance even though the time from the actual recording to the ADR session could be months or even years!. 

Foreign films obviously get dubbed in the language of the country they are being distributed to and so don't necessarily need to be in perfect sync. Though across Europe different countries have different rules, naturally. as seen on this map here.

Looping is also a name for dialogue replacement as the lines that need to be retaken will be done over several takes so the actor can get into the rhythm of the piece and deliver a better performance.

This is was a brief one as im in between filming,

Thanks for viewing, comments appreciated,

Matt Price

Film Job Sites

Hey all,


This is a quick blog with a couple of big job sites for films and a bit about them.


Mandy.com (worldwide)
Since 1994 this site offers jobs as postings such as classifieds for used equipment. It covers jobs around the world and with your own profile on the site you can be found by others. This enables you to get work from abroad as i have where the projects are in the UK. 
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Good: Free to apply to all jobs
Bad: Lots of expenses only student projects


Film Crew Pro (US, UK, Canada)
"Film Crew Pro was setup in late May 2009 to make the life of crew just a little bit easier. Although we can't guarantee you will get paid work or even tell you about every opportunity, we're going to do our best. We've combined the Blue Compass technology with feedback and advice from hundreds of film and TV professionals. Film Crew Pro is the result, a site which alerts you to upcoming employment opportunities and plugs you into the UK Film & TV community." - Film crew pro's own description
This also has forums and postings in classified like anywhere else and they are very useful, but more people should post in them to get them interesting.
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Good: Lots of proper paid jobs by need to pay £12 a month subscription (no fixed contract)
Bad: very good website but i guess you could complain it isn't free


Talent Circle (UK)
"Talent Circle launched in May 2003 with the simple aim of trying to help people working in film achieve more. The site was designed to be fresh, innovative and offer a real alternative to the other commercial offerings. Today, Talent Circle owned and operated by ScriptPlus Limited, which also runs the London Screenwriters Festival and the London Comedy Writers Festival as well as other workshops and events. ScriptPlus Limited is owned and Operated by Chris Jones." - Talent circles own description

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Good: Nice layout, some decent jobs

Bad: Most features aren't running like the classified ads.

Any more popular ones you use for jobs? then comment,

Thanks,

- Matt Price