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cafebabe (894)

cafebabe
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Journal of cafebabe (894)

The Fine Print: The following are owned by whoever posted them. We are not responsible for them in any way.
Friday July 07, 17

Test Data For Codecs

12:30 AM
Software

Test data for audio codecs:-

  • Boston: More Than A Feeling - Tom Scholz invented a sound engineering technique where vocals, lead guitar and base guitar are each recorded as four separate sessions. Two recordings are played hard left and two recordings are played hard right. This creates a phased sound which "pops" in a stiking enough manner to form a band and tour.
  • Alice Cooper: Poison - Noise and high dynamic range.
  • Foo Fighters: This Is A Call - Track 1 of the first album has some of Dave Grohl's expert drumming. Cooler than the Phil Collins drumming used as test data for MLP.
  • Trailer for Step Up 4 - Urban in a very Disneyfied manner. However, has a tortuous mix of voice, music, sirens and rumble in one track. May be available with stereoscopic video.

Test data for video codecs:-

Test Data For Codecs | Log In/Create an Account | Top | 6 comments | Search Discussion
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The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
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  • (Score: 0) by Anonymous Coward on Friday July 07 2017, @01:22AM (3 children)

    by Anonymous Coward on Friday July 07 2017, @01:22AM (#535958)

    Where's Tom's Diner [wikipedia.org]?

    Where's Big Buck Bunny [wikipedia.org]?

    • (Score: 0) by Anonymous Coward on Friday July 07 2017, @06:41PM (2 children)

      by Anonymous Coward on Friday July 07 2017, @06:41PM (#536208)

      Where's Lenna [wikipedia.org] ?

      • (Score: 2) by cafebabe on Saturday July 08 2017, @03:01AM (1 child)

        by cafebabe (894) on Saturday July 08 2017, @03:01AM (#536382) Journal

        I thought this type of imagary was considered sexist. Specifically, from https://en.wikipedia.org/wiki/Lenna [wikipedia.org]:-

        Before Lenna, the first use of a Playboy [wikipedia.org] magazine image to illustrate image processing algorithms was in 1961. Lawrence G. Roberts [wikipedia.org] used two cropped 6-bit grayscale facsimile scanned [wikipedia.org] images from Playboy's July 1960 issue featuring Playmate [wikipedia.org] Teddi Smith [wikipedia.org] (born Delilah Henry), in his MIT [wikipedia.org] master's thesis on image dithering [wikipedia.org].

        Despite this, I've used images of Avril Lavigne [wikipedia.org]. This is a particularly good source of varied, high-contrast textures [rex-fox.com].

        --
        1702845791×2

        • (Score: 0) by Anonymous Coward on Saturday July 08 2017, @05:41AM

          by Anonymous Coward on Saturday July 08 2017, @05:41AM (#536438)

          Missing the point, you are. Tom's Diner, Big Buck Bunny, and Lenna are widely regarded as standard test data.

          If you think Lenna is sexist, by all means use the Utah Teapot instead. But then, a teapot can be used as a sex toy.

          Avril Lavigne? Hey, hey, you, you, I don't like your test data. No way, no way, I think you need some other data.

  • (Score: 3, Informative) by shortscreen on Friday July 07 2017, @03:55AM

    by shortscreen (2252) on Friday July 07 2017, @03:55AM (#535996) Journal

    Years ago, before I had tinnitus, I did some test encodes with LAME and compared them to their uncompressed PCM counterparts to decide on a good bitrate. The recording which came out with the most noticable artifacts (ie. required the highest bitrate) was a music track from a software FM synthesizer.

  • (Score: 2) by cafebabe on Saturday July 08 2017, @02:42AM

    by cafebabe (894) on Saturday July 08 2017, @02:42AM (#536380) Journal

    Example data can be obtained via YouTube.Com using the Firefox web browser and the 1-Click YouTube Video Download plugin available via https://addons.mozilla.org/en-US/firefox/addon/1-click-youtube-video-downl/ [mozilla.org]. Audio can be stripped with ffmpeg, avconv or suchlike.

    • The trailer for Step Up 4: Miami Heat [youtube.com] was the original piece of test data because it has a challenging stereo mix of male and female voices, crowd noise, urban noise and street dance music.
    • Alice Cooper: Poison is an example of male lead vocals, female backing vocals, whining guitar and strong percussion.
    • Stiltskin: Inside is similar but features a Hammond organ sound.
    • Boston: More Than A Feeling [youtube.com] pioneered a technique of two sets of vocals/instruments on each of two channels to create a dynamic phased effect. Correlation between stereo channels is therefore incidental. This makes de-correlation particularly challenging.
    • Starship: Nothing's Gonna Stop Us [youtube.com] is a male/female duet with awkward vibrato and very high range on the percussion.
    • Foo Fighters: This Is A Call [youtube.com] is fast-paced grunge/punk with fuzzed guitars. It is particularly challenging test data because it has strong percussion with low stereo correlation.
    • Presidents Of The United States: Peaches [youtube.com] is similar.
    • AC/DC: Live At River Plate [bbc.co.uk]. Extended test. One hour live show with definitive recordings of AC/DC tunes.
    • Bob Marley: We're Jammin'. This is more suitable as a hardware test but it should be possible to hear the limitations of the analog mastering process.
    • The audio from Raum/Zeit (Space/Time) [youtube.com] is an example of sequenced music in which stereo correlation is low.

    It should be noted the recordings from different eras use stereo channels in different configurations:-

    • Vinyl recordings in the 1960s used each side of a groove to record an audio channel. This technique was upwardly and downwardly compatible with monophonic equipment. However, stereophonic equipment suffered from unintended cross-talk due to mechanical considerations.
    • In the early 1970s, four track analogue mastering systems allowed a subsonic channel to be formed by cross-wiring a bass speaker between stereo channels. Quadraphonic records also became available but the cross-talk was terrible.
    • From 1976 onwards, 16 track analog mastering systems allowed lone musicians to create symphonies (Mike Oldfield) or phased mixes (Tom Scholz).
    • The transition from vinyl singles to Compact Discs and the widespread use of karaoke machines created a shortfall of backing tracks. Therefore, it has become conventional to make a stereophonic mix such that it is possible to subtract one channel from the other channel and obtain a monophonic instrumental version suitable for karaoke. This requires all vocals to be centered and unphased and all instruments to be uncentered and/or phased. (This had moderate effect on Foo Fighters: This Is A Call and failed on Raum/Zeit due to the differing mixing conventions of sequenced music.)
    --
    1702845791×2
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