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Detta flöde har endast grunläggande felkorrigering

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• Filen ligger i det vanligaste fallet på en hårddisk. Hårddisken har interna CRC-checkar för att se till att data skrivs och läses rätt.


• På hårddisken finns filsystem. Filsystemen har felkontroller för att se till att data skrivs/läses korrekt.


• Data läses från hårddisken och skickas vidare till minnet, läsningen sker med felkontroll genom systemkomponenterna ovan.


• Data packas ihop i ett paket som sen skickas över nätverket - ofta Ethernet men även andra varianter finns - alla vanligt förekommande varianter har dock felkorrigering mha CRC.


• Protokollet som används för att skicka datat är oftast TCP/IP. TCP har felkorrigering för paketets data. IP har felkorrigering för IP-headern.

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konverterats till en ren PCM-ström

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playback paused: 55 ps
playing AIFF: 57 ps
playing FLAC: 57 ps
playing mp3: 58 ps
http://forums.slimdevices.com/archive/index.php/t-15882.html

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We have done extensive measurements on power supply disturbance recently, and have compared results for both FLAC and WAV streaming. Our findings are as follows :

1. If we measure the power rail that feeds the main processor in the DS we can clearly see identifiable disturbance patterns due to audio decoding and network activity. These patterns do look different for WAV and FLAC - WAV shows more clearly defined peaks due to regular network activity and processing, while FLAC shows more broadband disturbance due to increased (but more random) processor activity.

2. If we measure the power rails that feed the audio clock and the DAC we see no evidence of any processor related disturbances. There is no measurable difference (down to a noise floor measured in micro-volts) between FLAC and WAV in any of the audio power rails.

3. Highly accurate measurements of clock jitter and audio distortion/noise also show no difference between WAV and FLAC.
http://nwavguy.blogspot.com/2011/02/jitter-does-it-matter.html

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All test signals were in the FLAC and WAV formats residing on a notebook computer
...
Most of the jitter-related peaks are within 1.1KHz from the signal frequency. Taking the RMS sum of the peaks between 50Hz and 1.1KHz from the signal, the jitter is estimated to be roughly 50 ps rms or 300 ps peak-to-peak.
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It is surprising that this jitter pattern is consistent whether the data is streamed wireless or taken directly from an SD card or a USB drive. One might expect that jitter would be worse through wireless connection, but the fact that it is consistent regardless of the type of interface suggests that there is intelligent buffering taking place internally for the wireless stream.
http://www.anedio.com/index.php/article/squeezebox_touch

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fig.7 shows a similar spectral analysis of the Musical Fidelity X-DACV3's analog output while it was driven by the AirPort Express via the Monster TosLink cable. The noise floor has dropped by 4#8211;5dB, the word-clock jitter to a respectably low 258ps, which is actually better than the case with the standalone D/A processor driven directly by my PC's S/PDIF output
http://www.stereophile.com/digitalprocessors/505apple

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Upp till bevis! Presentera något som stöder tesen att skillnader mellan Wav och Flac uppstår. Intresse för ämnet verkar finnas, men hittills har ingen kavlat upp ärmarna och gjort ett försök.

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