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Topic: How do I know what encoder my M4A file has been converted to? (Read 4273 times) previous topic - next topic
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How do I know what encoder my M4A file has been converted to?

How do I know what encoder my M4A file has been converted to?

Re: How do I know what encoder my M4A file has been converted to?

Reply #1
Check metadata. You can use MediaInfo, foobar.........

You will see something like:
Writing application : fdkaac 0.6.3, libfdk-aac 3.4.22, CBR 128kbps (FDK)
Writing application : fhgaac v03.02.16;CBR=128000 (FHG)
Writing application : qaac 2.72, CoreAudioToolbox 7.10.9.0, AAC-LC Encoder, CBR 128kbps, Quality 96 (qaac/Apple)

Edit: That is for 'normal' files.

If your files were created/processed by another program (for example ffmpeg) or tags were removed it gets trickier.
Experts can use some tricks like spectrum analyzer and guess the encoder. For example Fraunhofer and LAME MP3 encoder - LAME will keep a lot more of
high frequency data.

There used to be a program called EncSpot for MP3 files, I dunno if there is something similar for AAC.
gold plated toslink fan

Re: How do I know what encoder my M4A file has been converted to?

Reply #2
General

Format                         : dash
Codec ID                       : dash (iso6/mp41)
File size                      : 4.95 MiB
Duration                       : 5 min 20 s
Overall bit rate               : 130 kb/s
Encoded date                   : UTC 2019-12-02 01:18:21
Tagged date                    : UTC 2019-12-02 01:18:21

Audio
ID                             : 1
Format                         : AAC LC
Format/Info                    : Advanced Audio Codec Low Complexity
Codec ID                       : mp4a-40-2
Duration                       : 5 min 20 s
Bit rate                       : 128 kb/s
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                    : 4.89 MiB (99%)
Title                          : ISO Media file produced by Google Inc.
Encoded date                   : UTC 2019-12-02 01:18:21
Tagged date                    : UTC 2019-12-02 01:18:21

 

Re: How do I know what encoder my M4A file has been converted to?

Reply #3
What encoder do you think Google uses?




Re: How do I know what encoder my M4A file has been converted to?

Reply #7
Experts can use some tricks like spectrum analyzer and guess the encoder.
Naoki Shibata and ff123 used to do that quite frequently. But that was when MP3 was the dominant format (i.e, for our geeky standards) and the then-available codecs (Blade, Xing, etc.) could be single-handedly counted.

Quote
There used to be a program called EncSpot for MP3 files, I dunno if there is something similar for AAC.
And so did Audio Identifier a bit later on, which accepted other formats. But Media Info (also available on Android) more than filled that gap these days. The former can be found on rarewares.org, [EDIT:] I mean, its spawn for even rarer birds, ReallyRarewares.
Listen to the music, not the media it's on.
União e reconstrução

Re: How do I know what encoder my M4A file has been converted to?

Reply #8
Where I can post my copyrighted samples? (It's YouTube Music, not YouTube, originally downloaded, not converted or remuxed)

Re: How do I know what encoder my M4A file has been converted to?

Reply #9
Unless you reduce them to <30-second clips, you cannot, for TOS compatibilty.

But, is it really necessary? Have you tried/read some of the tools/tips pointed out to you here?
Listen to the music, not the media it's on.
União e reconstrução

Re: How do I know what encoder my M4A file has been converted to?

Reply #10
Unless you reduce them to <30-second clips, you cannot, for TOS compatibilty.

But, is it really necessary? Have you tried/read some of the tools/tips pointed out to you here?

Yes, tried all, there's nothing to show about AAC encoder on those tools.
I can't edit that file, because remuxing or editing the file will change the original file.
Can I DM you?

Re: How do I know what encoder my M4A file has been converted to?

Reply #11
As long as it's TOS compliant you could. But unlike others who've also replied so far, I'm not that knowledgeable with AAC and would end up not being that much helpful. So your best bet IMO, is to wait for them to chime in.
Listen to the music, not the media it's on.
União e reconstrução

Re: How do I know what encoder my M4A file has been converted to?

Reply #12
You can use ffmpeg: ffmpeg -i input.m4a -codec copy -ss xx:xx:xx -to xx:xx:xx output.m4a
Replace xx with desired time - hh/mm/ss. Like includemeout said, make sure it is under 30 seconds.
Please use some well known song because we (me) need lossless version so we can compare it.

Edit: My brain sometimes stops working - I blame heat...

They will be using either fhg or fdk.
I just encoded couple of files and fhg cuts at 16 kHz and fdk cuts at 18 kHz. (128 CBR)
You can use Spek to analyze couple of files. Probably easiest method.

Edit 2: It is FhG. He sent me sample.
gold plated toslink fan

Re: How do I know what encoder my M4A file has been converted to?

Reply #13
Thanks for testing. The question that arises is why Google used the official encoder? (It's 128Kbs, VBR, 44.1Khz, 16Bit)

Re: How do I know what encoder my M4A file has been converted to?

Reply #14
Personal preferences apart, why shouldn't they?

Which compels me to ask you: any reason why you want to know it so badly?  Genuine curiosity only?

Not that there is any harm in asking it, :) it's just that the answer may be more down to some dull corporative decision than any other more commonsensical one.
Listen to the music, not the media it's on.
União e reconstrução

Re: How do I know what encoder my M4A file has been converted to?

Reply #15
Thanks for testing. The question that arises is why Google used the official encoder? (It's 128Kbs, VBR, 44.1Khz, 16Bit)
Correction: it's lossy now, bit depth is not applicable anymore.
Listen to the music, not the media it's on.
União e reconstrução

Re: How do I know what encoder my M4A file has been converted to?

Reply #16
Google has done this because it can not be found better than FhG.

Re: How do I know what encoder my M4A file has been converted to?

Reply #17
Whatever that means.

With your dodging the two previous questions, methinks your quest has come to an end.
Listen to the music, not the media it's on.
União e reconstrução

Re: How do I know what encoder my M4A file has been converted to?

Reply #18
Wrong. They are using FhG not because of quality - but because of licensing.
Apple's encoder has highest quality. Apple is Google's competitor and there is no way Apple will allow them to use their encoder.
Other encoders like Nero, ffmpeg... are either lower quality / not actively developed / not properly tested.
The only other options are either FDK or FhG.
FDK has been optimized for portable devices and has lower quality than FhG so they had to choose FhG.

Edit:
why you want to know it so badly?  Genuine curiosity only?

This. Do you plan to use files downloaded from YouTube Music for your library?
Not a single audiophile will use 128 kbit/s CBR AAC-LC for serious listening.
There are many different ways to get higher quality files.

Edit 2: Sample that you sent me has very bad clipping problem. They are not even properly encoding lossy files.



Stick to lossless and create lossy file by yourself.
gold plated toslink fan

Re: How do I know what encoder my M4A file has been converted to?

Reply #19
Exactly, never expect Google to license Apple's tech.
It's 128~ VBR.
Google has never cared about quality, it just thinks about reducing costs!
Soon all streaming services will offer HiFi plan. (FLAC, of course you should pay for it)

Re: How do I know what encoder my M4A file has been converted to?

Reply #20
Do you plan to use files downloaded from YouTube Music for your library?
Not a single audiophile will use 128 kbit/s CBR AAC-LC for serious listening.
There are many different ways to get higher quality files.

The unoptimal codec is compounded by the low bitrate of YouTube audio. It's almost false advertising to let you select 720p, 1080p, 1440p, 2160p, and yet the audio is as shitty as ever.

Re: How do I know what encoder my M4A file has been converted to?

Reply #21
Mobile version of YTM supports 256kbps (VBR), but not the web version.

Re: How do I know what encoder my M4A file has been converted to?

Reply #22
Do you plan to use files downloaded from YouTube Music for your library?
Not a single audiophile will use 128 kbit/s CBR AAC-LC for serious listening.
There are many different ways to get higher quality files.

The unoptimal codec is compounded by the low bitrate of YouTube audio. It's almost false advertising to let you select 720p, 1080p, 1440p, 2160p, and yet the audio is as shitty as ever.
YouTube's switch to Opus on the web was a good start... but they did it largely as means to keep the average audio rate close to 128k. Why not 256 for audio codecs when HD? Part of that I think is because of the auto-switching of video quality when network bandwidth is low for real-time, that switching audio streams isn't seamless. (That doesn't mean the audio stream couldn't be fixed to a higher rate when the user explicitly requests HD.) Another part is most people find 128k acceptable enough to not demand better... especially if YouTube's best quality is better than a lot of the other sources out there, including the CW streaming site.