FFMPEG version vs audio quality

[Jeffry67]

I recently explored HDCD transcoding and to do this I had to install the ffmpeg package from SynoCommunity (that’s version 4.2.1-23 of ffmpeg). I finally abandoned the HDCD transcoding because it wasn’t worth it.

Since then I’m using this version of ffmpeg transcoder on my Synology NAS instead of the built-in DSM version (I don’t know which version number they are using).

In short, I’m using this:

Stream.converter = /volume1/@appstore/ffmpeg/bin/ffmpeg

Instead of:

Stream.converter = ffmpeg

I haven’t done full comparison but it seems that the SynoCommunity version of ffmpeg has a better sound, it seems to be softer, richer and with more minute details.

Should there be audible differences when using different versions of ffmpeg? If so, why? I thought that the decoding was bit-perfect!

The drawback with using ffmpeg v 4.2.1 is that the aac transcoding (aac:wav24 doesn’t work anymore. The tracks can’t be played and the log shows: Converter program ended unexpectedly with exit value 1

Thank you,
Jean-François

[orange55]

(07-02-2020 16:54)Jeffry67 Wrote:  The drawback with using ffmpeg v 4.2.1 is that the aac transcoding (aac:wav24 doesn’t work anymore. The tracks can’t be played and the log shows: Converter program ended unexpectedly with exit value 1

That is interesting, do any of the other transcoding work? As I might give it a try to see how it sounds.

This is what I currently transcode;

aac:wav24;96,alac(16):wav24;96,alac:wav24;96,flac(16):wav24;96,flac:wav24;96,mp3​:wav24;96

[Jeffry67]

Hi, Transcoding works (with ffmpeg v4.2.1) with FLAC, ALAC and MP3.
This is my transcode options: flac:wav24;, alac:wav24;, mp3:wav24;

It doesn't work with AAC and MP4.

for AAC I tried : aac:wav24 (without the comma) and according to MinimStreamer documentation it should use own MinimStreamer transcoder but it gives me the same error message.

Give it a try and I'm looking forward to know what you think of the sound difference (if any).

Your are transcoding everything to 96 khz, is it because of your setup? Any benefits doing that? Also, I see that you are isolating 16 bits "flac(16):wav24;96" from 24 bits "flac:wav24;96", why do this?

Jean-François

[orange55]

I have tried v4.2.1 and yes it does improve sound quality. It's not night and day but there is a difference and worth the upgrade.

I would describe it as a more transparent and therefore you are hearing more detail which is turn seems to provide more bass, but I think that is more the extra detail and texture of the bass coming through. Background sounds seem to be easier to hear. It is more "relaxed", rather than "softer". Great tip, thanks.

I have found that by converting all files to wav24:96 it gives a better sound, more darkness to the sound. I have found this on multiple DACS not just one so I recommend giving it a go.

I have now cleaned up my transcoding as there were some old settings in there which were from experimenting in the past. Here is now what it looks like.

aac:wav24;96,alac:wav24;96,flac:wav24;96,mp3:wav24;96

Finally I too have found that AAC does not work, get the following error: Converter program ended unexpectedly with exit value 1

[simoncn]

For some reason, this SynoCommunity build of FFmpeg refuses to open an AAC-encoded audio stream. I have tried enabling extra diagnostics but there is no message giving a reason for this. Instead, you can use builds from this website, which work correctly with AAC-encoded audio.

For mp4 and aac transcoding, an external converter program (ffmpeg) is always used. The comment about removing the semicolon to use the internal converter applies only to FLAC files but this is not made clear. I will reword this section to clarify this.

[Jeffry67]

Hi

@orange55: I did some more listening and it really improves the sounds like you described it. The sense of depth is more pronounced. Glad that it works for you also! I'll try for sure converting to 96khz.

@Simon: thanks for the info. I'll try installing the version of ffmpeg you propose.

[orange55]

@Simon. Thanks for the feedback.

@Jeffry67, which version of the software do I need? Thanks.

[Jeffry67]

Hi orange55, Among the 4 builds I took the "armel" version (I have a Synology DS 216j with a Marvell Armada 385 processor). It really depends on the processor of your NAS. I did it by trial and error and the armel worked well and yes, the AAC encoding to WAV24 works now.

I followed the instruction in the "FAQ" link to install.

[orange55]

Great. I have the same processor will give it a go later.

Thanks.

[simoncn]

It is better to use the armhf version for an Armada 385 as this will perform floating-point calculations more efficiently.

The simplest way to find the correct version is to look at this section. If the processor of your NAS is listed as ARMv7, you should use the armhf version of FFmpeg. For ARMv5 processors, you should use armel. For ARMv8 processors, you should use arm64. For Intel processors, you should use normally use amd64. If this doesn't work, use i686.

EDIT: The armhf version doesn't work on an Armada 385. This armhf build has used a compiler that generates Thumb-2 instructions, which aren't available on the Armada 385. It would work on some ARMv7 devices but not this one. To avoid running into this, the safest approach is to use the armel version on all Synology ARMv7 devices.