Home > Computer (HW and SW) > iTunes 11.0.2-11.0.4 Playback Bitrate

iTunes 11.0.2-11.0.4 Playback Bitrate

Just downloaded the latest version of iTunes. Noticed a new playback panel:

iT1002

Seems you can up-sample your content within iTunes using Apple’s SRC. I did a quick comparison vs 44.1K/16bit and preferred the up-sampled playback… I realize that you can’t add data back to the original file, but playing at a higher sample rate will change the digital filtering applied in the DAC.

To allow direct playback of the iTunes up-sampled stream, you need to match the sample rate in the sound control panel. Otherwise, Windows will re-sample the stream to match the setting. This is because iTunes only supports WASAPI SHARED mode.

wasapiShared

Having the Hifiduino controller show the incoming sample rate, helps tremendously in the set up and configuration of different audio players and their options.

Here is the Playback panel of the previous version

iT10xPlayback

UNDOCUMENTED FEATURE

Apple has yet to document the new playback panel in the latest iTunes 11.0.2. If you search their website or the help files, there is no mention of this new option. Maybe this is work in progress and there is more to come in newer versions of iTunes. As it is,  it  works straightforwardly by determining the audio output sample bit rate and bit depth during playback.

Since iTunes 10.5, the Quicktime component is not included in the installation [link]. This means that this new playback bit-rate feature is NOT quite a replacement for the bit-rate options in Quicktime (since Quicktime has not been required for a while).

Below is the Quicktime control panel showing the Sound Out bit rate control which is only available with Direct Sound. If choosing WASAPI, no bit rate control is available.

QTSample

QTSample2

Which begs the question: without the Quicktime control, what default mode was iTunes using?

SWEET SPOT?

Having never supported WASAPI exclusive mode, iTunes will re-sample every track to the sample rate set by the player. Audio purists will immediately see this a not bit perfect. However, upsampling everything may not be a bad thing. Benchmark Media has been encouraging using iTunes upsampling for some time now [link]:

Sample rate can be set to match the sample rate of the media or to the highest that the audio interface is capable, since the upsampling in iTunes is harmless… The user should not be discouraged from setting the sample-rate to 96 kHz as a permanent setting, even when the audio is less then 96 kHz.

Further, the Sabre32-based DAC, seems to have a sweet spot with higher input sample rate. Thus the higher sampling rate seems to be specially beneficial to Sabre32-based DACs.

MORE LISTENING TESTS

I spent some more time comparing 11.0.2  iTunes playback at “bit-perfect”, in this case 44.1K material vs. upsampled to 192K/24

Even though I am not one that has the capability to detect minute differences (for example by changing a passive component such as a capacitor or a power supply), this time I was able to readily hear differences between the two playback sample rates. In all cases, I preferred the upsampled playback. This says that the differences are not minute.

The 192K/24 playback provided the following improvements:

  • A more 3D soundstage. Some would say more “holographic”
  • More detailed resolving of the sound.  The same sounds, but “finer”, more “delicate”, or some may say “super high resolution”.
  • The harmonics gave a “greater presence” of the music. Perhaps greater dynamics.

EFFECT OF FILTERS?

I am sure there is no magic with the Apple upsampling algorithm, and there is no way to add information that in not there to start with. The only other explanation for the improvement is the use of different filters in the Sabre32 DAC.

MORE INFO

http://www.qobuz.com/info/MAGAZINE-ACTUALITES/HI-FI-PRATIQUE/iTunes-et-le-24-bits-a-192-kHz-oui173410

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  1. xyz
    2013/04/10 at 09:32

    I have a not so relevant question about itunes (possible first time buyer of iphone)
    Is it possible to transfer media to iphone eg songs, without having them stored to your pc, but have them stored in a server?

  2. Con
    2013/07/16 at 07:36

    Right up sampling for 44,1 Khz material should be done at 176,4Khz, but not 192Khz…

    • BlgGear
      2013/07/16 at 17:57

      I think it depends on the resampling algorithm. I’ve heard the resampler from Quicktime is pretty good.

  3. Con
    2013/07/16 at 07:49

    I may suggest this experiment:

    -Take a good CD recording on 44,1Khz (best an DXD recording).
    -Rip it with EAC to wav uncompressed
    -Up sampling the wav file to 176,4Khz 64bit (Adobe Audition – wav R64). Save it as wav
    -Open Foobar last update with FLAC 1.3 (this version can convert R64 wav). Convert that saved wav file to Flac 24bit.
    -Listen it… and come back with impressions.

    • BlgGear
      2013/07/16 at 17:58

      Thanks for the tip. Shall try it sometime…

  4. Anonymous
    2013/10/02 at 22:09

    I come across this blog while in the work of install a component Wasabi to my FooBar2000. I want to comment that setting my iTune 11.1 to 24bit and upsample rate to 192khz were both positive improvement in the sound output performace.

  5. Anonymous
    2013/10/02 at 22:18

    continue from commnet #7:
    I have made change incrementally from 16-24-16 bit and the output resolution was better on the 24 bit setting. My system uses the MF VDAC II from my Dell Latitude USB to a pre-amp aux inputs.

    The 192khz setting was also improved from the 44.1khz. I have tried that in either case a and have heard the improvement. The combined improved of the bitrate and sampling rate was not minute.

    • BlgGear
      2013/10/10 at 00:33

      Thanks for sharing. I am using 192K output all the time.

  1. 2013/07/15 at 22:38

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