Rekordbox 5.4.2 problems wit m4a files

wow, thanks for figuring that out!

I had no idea, the encoding bit would have something to do with it since Virtual DJ, Serato and Traktor DJ loaded these tracks without any problem.

¯\_(ツ)_/¯

Now i'm looking for a way to prevent my Flac to m4a conversions to become 32 bits but can't even find out how much bits they have! :-) See Media inspector on screenshot.

Or is it "Codec (FourCC): 40" what indicates the bits per sample?

Also, in XLD, there is no setting to choose from. Strange... Also so strange only recordbox is having problems with these 2 audiofiles... I just played them as a fourth test (after Serato, VDJ en Traktor DJ) in algoriddim's djay Pro application. Also no problem. Weired, very weired, only rekordbox is having problems with them.

- What is the application info you made a screenshot from?

I think that Codec 40 is just a reference to its internal list.

The screenshot I used was from the info sheet from VLC (such a powerful, yet simple tool!).

What is the application you're using to convert FLAC > AAC?

oh, i see, you use VLC for checking the bits per sample of an audio file on Mac.

Well, i'm quitte sure what VLC shows concerning bits per sample information is wrong  according to the test i just did with two more files in VLC, a regular mp3 (titled 'Psychosocial'  and a m4a (Tittled 'Time') bougt in the iTunes store. Both extra files are no problem in RekordBox. But According to VLC, these two extra test files are also 32 bits per sample.

Accurate information it seems, is given by the app 'Fakin the funk'. All four files are 16 bits per sample. See screenshot.

Edit: Answering your question: "What is the application you're using to convert FLAC > AAC?"

The application i'm using for many years is XLD (link), as written in my first post. Never had or have any issues with it. All the files i converted with it are no problem for Serato, VDJ, Traktor and algoriddim's Djay Pro.

You know that "Fakin the Funk" is used to analyse the audio and determine its true nature, it doesn't represent the actual audio file bit depth / sample rate. Its purpose is to show when a file has been falsely "up-sampled." In the case of Psychosocial, the file itself is a 32bit/44.1kHz M4A, but the original source before conversion was only 16bit/44.1kHz -- so it's been encoded higher than it needs to be.

I'm digging a bit more into this, leave it with me.

Okay, so in my research this evening, I've learned that the M4A (AAC) files themselves don't have a bit-depth per-se, it's the decoder that would assign the bit depth, which is typically a maximum of 32bits (floating) to provide the maximum quality while decoding.

Here's what I got when running the files through MediaInfo (available in the app store for $0.99 ... also available for free, but worth the buck for the updated interface):

General
Complete name : /Users/Pulse/Desktop/Two difficult m4a files for recordbox 5/02 Promises.m4a
Format : MPEG-4
Format profile : Apple audio with iTunes info
Codec ID : M4A (M4A /mp42/isom)
File size : 9.29 MiB
Duration : 3mn 33s
Overall bit rate mode : Variable
Overall bit rate : 365 Kbps
Album : Media Markt * Top 40 * 2018 * Week 36 *
Track name : Promises
Track name/Position : 2
Track name/Total : 50
Grouping : Ultratop 50 - 10 dec. 2018; Per decennia beoordeeld; Print;
Performer : Calvin Harris & Sam Smith
Genre : Dance-house best
Recorded date : 2018
Encoded date : UTC 2018-09-12 13:01:53
Tagged date : UTC 2019-01-12 09:58:19
Writing application : X Lossless Decoder 20170729, QuickTime 7.7.3, True VBR Quality 127
BPM : 123
Cover : Yes
Encoding Params : (Binary)
LABEL : peak time
initialkey : Ebm
publisher : peak time
rating wmp : 204
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relvol : YXBwbGljYXRpb24vb2N0ZXQtc3RyZWFtAABTZXJhdG8gUmVsVm9sQWQAAQEBAAAA
videoassociation : YXBwbGljYXRpb24vb2N0ZXQtc3RyZWFtAABTZXJhdG8gVmlkQXNzb2MAAQEBAAAA
IsTruncated : Yes

Audio
ID : 1
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 3mn 33s
Bit rate mode : Variable
Bit rate : 353 Kbps
Maximum bit rate : 387 Kbps
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 KHz
Frame rate : 43.066 fps (1024 SPF)
Compression mode : Lossy
Stream size : 9.06 MiB (98%)
Language : English
Encoded date : UTC 2018-09-12 13:01:53
Tagged date : UTC 2019-01-12 09:58:19

And...

General
Filename : 24 Djadja.m4a
Format : MPEG-4
Format profile : Apple audio with iTunes info
Codec ID : M4A (M4A /mp42/isom)
File size : 6.94 MiB
Duration : 2mn 50s
Overall bit rate mode : Variable
Overall bit rate : 342 Kbps
Album : Media Markt * Top 40 * 2018 * Week 36 *
Track name : Djadja
Track name/Position : 24
Track name/Total : 50
Grouping : Ultratop 50 - 10 dec. 2018; badhuis
Performer : Aya Nakamura
Recorded date : 2018
Encoded date : UTC 2018-09-12 13:01:30
Tagged date : UTC 2018-12-10 22:02:14
Writing application : X Lossless Decoder 20170729, QuickTime 7.7.3, True VBR Quality 127
BPM : 98
Cover : Yes
Encoding Params : (Binary)
LABEL : warm up
initialkey : Cm
publisher : warm up
rating wmp : 255
analysisVersion : YXBwbGljYXRpb24vb2N0ZXQtc3RyZWFtAABTZXJhdG8gQW5hbHlzaXMAAgGA
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beatgrid : YXBwbGljYXRpb24vb2N0ZXQtc3RyZWFtAABTZXJhdG8gQmVhdGdyaWQAAQAAAAABPUCDEkLE / AAAA
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relvol : YXBwbGljYXRpb24vb2N0ZXQtc3RyZWFtAABTZXJhdG8gUmVsVm9sQWQAAQEBAAAA
videoassociation : YXBwbGljYXRpb24vb2N0ZXQtc3RyZWFtAABTZXJhdG8gVmlkQXNzb2MAAQEBAAAA
IsTruncated : Yes

Audio
ID : 1
Format : AAC LC
Format/Info : Advanced Audio Codec Low Complexity
Codec ID : mp4a-40-2
Duration : 2mn 50s
Bit rate mode : Variable
Bit rate : 333 Kbps
Maximum bit rate : 394 Kbps
Channel(s) : 2 channels
Channel layout : L R
Sampling rate : 44.1 KHz
Frame rate : 43.066 fps (1024 SPF)
Compression mode : Lossy
Stream size : 6.75 MiB (97%)
Language : English
Encoded date : UTC 2018-09-12 13:01:30
Tagged date : UTC 2018-12-10 22:02:14

Two things stood out... First, they've both been run through Serato (hence that massive pile of extra data) - that's not a problem. More of a problem is the second thing - they are both noted as IsTruncated : Yes

So I tried running them through an ffmpeg conversion which changes the container type but retains the audio data without re-compressing it and losing anything else, it also strips away virtually everything else:

ffmpeg -i old_file_name.m4a -acodec copy new_file_name.aac

But when doing so, the output file (whether AAC, WAV, MP3) would not import to rekordbox. When I transcoded it to a WAV file using:

ffmpeg -i old_file_name.m4a new_file_name.wav

...it created a new (larger) wave file at 16/44.1.

I could then import that wave file to rekordbox and it would build the overview and beat grid. So clearly the problem is corrupt data (or rather the corrupt file causes rekordbox to hate life and terminate itself).

You can convert the file, or if you still have the original, convert it again. If you want to use ffmpeg, I recommend doing so via Homebrew.

Long story short ... you may want to use a different tool to convert those files... and ffmpeg can do it for you, even as a batch process.