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[rjm]

I was unable to get MC to play aac audio today.

I searched the forums and followed various advice such as FFDShow settings, DC-Bass Filter, ensuring Quicktime installed, etc. etc.

I am not asking for a response nor a fix because I said to heck with it and transcoded the files to mp3.

Just want to make you aware that aac audio support is problematic.

[Alex B]

I agree.

You didn't ask for a response, but here's how to configure the DC-Bass source filter:

- Install DC-Bass Source.

In MC13:

- Options > File Types > AAC audio (m4a, m4p, m4b, aac):
  Playback Method: JRiver audio engine (using DirectShow filter)

  and

- Options > Playback > Video > DirectShow playback settings:
  DirectShow filters: m4a (set also aac if you have raw AAC files):
  Source filters: DC-Bass Source (only this is needed)

I attached a screenshot of the DS settings. The other filters I have selected in the right part of the window are optional. "Use JRiver Audio Renderer" makes possible to analyze the files and use internal volume & other DSP features.

[rjm]

Thanks Alex.

I definately had the DS options set as you described.

Not sure about

Options > File Types > AAC audio (m4a, m4p, m4b, aac):
  Playback Method: JRiver audio engine (using DirectShow filter)

Do you mean Options\File Associations ?

Not sure if this clue is helpful, but Quicktime and BSPlayer would not play the files, and VLC Player (which comes with its own codecs) would.

I normally avoid aac like the plague but really wanted this one. Fortunatley I was able to transcode it nicely to mp3.

[lalittle]

Just so I fully understand this conversation, are you saying that these steps are now necessary in order to play any aac file?  The reason I ask is because didn't have to do this with MC12 -- these file types just played by default for me.  Is MC13 somehow different in this regard, or am I unaware of something I did to get the files to play with MC12?

Thanks,

Larry

[Alex B]

Do you mean Options\File Associations ?

No.

The "file associations/types" configuration options have changed in the build 69. See the attached screenshot.


Do you know what is the exact format of the AAC files? Are they encoded in the most common LC-AAC format or perhaps in the HE-AAC format? Are the files in MP4 container format (usually .mp4 or .m4a) or are they raw AAC (.aac)?

[Alex B]

Just so I fully understand this conversation, are you saying that these steps are now necessary in order to play any aac file?  The reason I ask is because didn't have to do this with MC12 -- these file types just played by default for me.  Is MC13 somehow different in this regard, or am I unaware of something I did to get the files to play with MC12?

By default MC12 and MC13 use QuickTime for m4a/aac playback. The decoded output does not come back to MC's internal playback engine when QT is used.

When a DirectShow decoder is used instead of QT the decoded output can be redirected to MC. That makes possible to use Internal Volume & other DSP features, output mode options (e.g. ASIO can be used), file converter, file analyzer & Volume Leveling, audio CD burner, and visualizations.

[rjm]

I am not sure what is the best way to determine aac properties so I will report what I can...

file extension: aac

Reported by MediaCoder:
- type: MPEG-4 AAC
- container: ADTS
- audio: AAC/AAC+, bitrate: 128 kbps, sample rate: 44100 Hz, channels:2

Reported by VLC media player:
- codec: mp4a
- channels: 2
- sample rate: 44,100 Hz
- AAC extension: SBR+PS

[Alex B]

SBR+PS

This means it is HE-AAC v2.

From Wikipedia:

HE-AAC version 1 (HE-AAC v1) uses spectral band replication (SBR) to enhance the compression efficiency in the frequency domain. HE-AAC version 2 (HE-AAC v2) couples SBR with Parametric Stereo (PS) to enhance the compression efficiency of stereo signals.

QT can play only LC-AAC files (the SBR part of HE files is ignored). In addition, I think it supports only AAC files that are in MP4 containers (.m4a or .mp4). DC-Bass should be able to decode all variants.


EDIT

ADTS

From Hydrogen Audio:

AAC can also exist in ADTS, which has sync headers nearly identical to those in MP3. It has the main advantage of being streamable. It usually known as MPEG-2 AAC, although you can stream MPEG-4 AAC in this format also. SHOUTcast AAC stations use ADTS.

I attached a small HE-AAC v2 / ADTS sample. I can play it correctly when MC13 is configured to use DC-Bass Source.

[Alex B]

I tested a few ADTS AAC files on QT Player. Here's what I found out:

QuickTime can play untagged LC-AAC/ADTS files correctly, but if the files contain APE tags it doesn't recognize them. The HE part is always ignored and if the file contains a PS part it is ignored as well and the file shows up as a mono LC file.

[rjm]

Your sample behaves the same as my aac. Does not play in MC and QT, does play in VLC.

fyi, my QT is a little out of date (7.5) but I do not want to update it because it comes bundled with iTunes.

[Alex B]

It is not going to work with QT. You can remove the APE tags with e.g. Mp3tag (a freeware tagger program), but even then QT will play only a part the full frequency range and in mono.

You would need to use a correctly configured DirectShow filter to play HEv2 files.

[fitbrit]

I've had great success with using CoreAAC DS filter for decoding AAC audio. I believe it's a free download found by simply typing CoreAAC in Google.

[Frobozz]

fyi, my QT is a little out of date (7.5) but I do not want to update it because it comes bundled with iTunes.

Apple does have a download for QuickTime without iTunes.  It's there, but you have to hunt a little.

An easier way to find it is to get it from FileHippo: QuickTime download

QuickTime is one that you want to keep updated cause there are remote exploits for some older versions.  There's an advisory for version 7.50 that is rated "highly critical" cause it can be remotely exploited: Secunia advisory: Apple QuickTime Multiple Vulnerabilities

[Alex B]

A newer QT version would not solve this specific problem.

[bspachman]

Not intentionally trying to derail the conversation about the playback of AAC files, but although playback works well for me--there's still no word or evidence about tagging these files...

brad