Quantcast

eac3 encoding

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
5 messages Options
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

eac3 encoding

Mike Brown
I just started digging into eac3 encoding and have been googling this and
that and have come up with:

ffmpeg -i front_left.wav -i front_right.wav -i front_center.wav -i lfe.wav \
-i back_left.wav -i back_right.wav \
-filter_complex "[0:a][1:a][2:a][3:a][4:a][5:a]amerge=inputs=6[aout]" \
-map "[aout]" -acodec eac3 -ab 999k outputfile.ac3

What I haven't been able to find are the available bitrates for eac3.
Obviously the normal ac3 bitrates up through 640kbps, but I do not know
what is available higher than that.  The 999k above is just a place holder.

Thanks.

MB
--
e-mail: [hidden email] | [hidden email]            /~\ The ASCII
        [hidden email] (140 char limit)       \ / Ribbon Campaign
Visit - URL: http://vidiot.com/                           X  Against
             http://vidiot.net/                          / \ HTML Email
"You're Sherlock Holmes, wear the damn hat!" - Watson to Sherlock
Sherlock - The Abominable Bride - 1/01/16
_______________________________________________
ffmpeg-user mailing list
[hidden email]
http://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: eac3 encoding

Moritz Barsnick
On Mon, Feb 13, 2017 at 15:25:39 -0600, Mike Brown wrote:
> What I haven't been able to find are the available bitrates for eac3.
> Obviously the normal ac3 bitrates up through 640kbps, but I do not know
> what is available higher than that.  The 999k above is just a place holder.

I don't see any restriction in the code, and the standard doesn't seem
to imply any restriction either:

  What is the full range of data rates for Dolby Digital Plus?

  Dolby Digital Plus can scale from 32 kbps all the way up to 6 Mbps. A
  typical range for Dolby Digital Plus on high-definition optical discs
  is 768 kbps to 1.5 Mbps.

(From
https://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/dolby-digital-plus-faq.pdf)

Moritz
_______________________________________________
ffmpeg-user mailing list
[hidden email]
http://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: eac3 encoding

Mike Brown
On Mon, Feb 13, 2017 at 10:43:09PM +0100, Moritz Barsnick wrote:

> On Mon, Feb 13, 2017 at 15:25:39 -0600, Mike Brown wrote:
> > What I haven't been able to find are the available bitrates for eac3.
> > Obviously the normal ac3 bitrates up through 640kbps, but I do not know
> > what is available higher than that.  The 999k above is just a place holder.
>
> I don't see any restriction in the code, and the standard doesn't seem
> to imply any restriction either:
>
>   What is the full range of data rates for Dolby Digital Plus?
>
>   Dolby Digital Plus can scale from 32 kbps all the way up to 6 Mbps. A
>   typical range for Dolby Digital Plus on high-definition optical discs
>   is 768 kbps to 1.5 Mbps.
>
> (From
> https://www.dolby.com/uploadedFiles/Assets/US/Doc/Professional/dolby-digital-plus-faq.pdf)

Thanks.  I failed to look at dolby.com, but still needed to know if there
were any restrictions in the code.

MB
--
e-mail: [hidden email] | [hidden email]            /~\ The ASCII
        [hidden email] (140 char limit)       \ / Ribbon Campaign
Visit - URL: http://vidiot.com/                           X  Against
             http://vidiot.net/                          / \ HTML Email
"You're Sherlock Holmes, wear the damn hat!" - Watson to Sherlock
Sherlock - The Abominable Bride - 1/01/16
_______________________________________________
ffmpeg-user mailing list
[hidden email]
http://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: eac3 encoding

Moritz Barsnick
On Mon, Feb 13, 2017 at 15:49:34 -0600, Mike Brown wrote:
> > I don't see any restriction in the code, and the standard doesn't seem
> > to imply any restriction either:
> Thanks.  I failed to look at dolby.com, but still needed to know if there
> were any restrictions in the code.

Sorry, I failed to see the restriction. ffmpeg will tell you if you
happen to enter an illegal one:

At 48k samplerate:
[eac3 @ 0xbe08920] invalid bit rate. must be 3008 to 6144000 for this sample rate
At 44.1k samplerate:
[eac3 @ 0xb9f3b40] invalid bit rate. must be 2768 to 5644800 for this sample rate

The actual formula is:
            max_br = 2048 * s->sample_rate / frame_samples * 16;
            min_br = ((s->sample_rate + (frame_samples-1)) / frame_samples) * 16;

I assume it is a restriction of the codec (of how it is defined), not
of the encoder.

Moritz
_______________________________________________
ffmpeg-user mailing list
[hidden email]
http://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Reply | Threaded
Open this post in threaded view
|  
Report Content as Inappropriate

Re: eac3 encoding

Mike Brown
On Mon, Feb 13, 2017 at 10:57:07PM +0100, Moritz Barsnick wrote:
> Sorry, I failed to see the restriction. ffmpeg will tell you if you
> happen to enter an illegal one:
>
> At 48k samplerate:
> [eac3 @ 0xbe08920] invalid bit rate. must be 3008 to 6144000 for this sample rate

3kbps?  Your previous email mention the Dolby spec going down to 32kbps.

Not that it makes a difference, as I would never go that low.  I'd just use
ac3 for bitrates of 640kbps and lower.

Thanks for the update.

MB
--
e-mail: [hidden email] | [hidden email]            /~\ The ASCII
        [hidden email] (140 char limit)       \ / Ribbon Campaign
Visit - URL: http://vidiot.com/                           X  Against
             http://vidiot.net/                          / \ HTML Email
"You're Sherlock Holmes, wear the damn hat!" - Watson to Sherlock
Sherlock - The Abominable Bride - 1/01/16
_______________________________________________
ffmpeg-user mailing list
[hidden email]
http://ffmpeg.org/mailman/listinfo/ffmpeg-user

To unsubscribe, visit link above, or email
[hidden email] with subject "unsubscribe".
Loading...