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17th January 2021, 11:46 | #1 | Link |
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Encode Dolby Digital Plus Audio (E-AC3)
I have a PCM file (2.0 / 24bit / 2304 kb/s). I want to transcode it to E-AC3 2.0ch (DD+ 2.0). What bitrate should I choose for that E-AC3 file?
I don't have much experience for this, hope to receive your help! Thanks very much ! |
17th January 2021, 15:08 | #2 | Link |
Big Bit Savings Now !
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Bandwidth restrictions: How much bitrate can be transmitted ? Give as much bitrate as you can, minus a safety margin.
Quality restrictions: How much degradation of resulting file can be tolerated ? Give as much bitrate as you can. Media restrictions: What media the resulting file shall be stored upon ? Read up media/container manuals, respect their restrictions. Player restrictions: On which player the resulting file shall be played ? Read up player's manuals, respect their restrictions. Filesize restrictions: Running out of space ? Give as low bitrate as you can. Now you decide about your preferences vs. their priorities.
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19th January 2021, 11:15 | #6 | Link |
Life's clearer in 4K UHD
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For the sake of clarity... Do you want to transcode or encode?
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20th January 2021, 03:40 | #7 | Link |
Derek Prestegard IRL
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Which encoder are you using?
The official Dolby encoder should give good quality at or above 128 Kbps. The rule of thumb with vanilla AC-3 was 192 Kbps, so I'd probably either just do that or maybe a hair lower like 160 |
20th January 2021, 06:51 | #8 | Link |
SuperVirus
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Interesting, EAC3 just like DTS's d.c.a. is not limited to a small "finite" set of ready-made bitrates, but most people keep using the well-known values from the old AC3 or/and from the MP3 era anyway
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20th January 2021, 07:23 | #9 | Link |
Derek Prestegard IRL
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Many production encoders have a fixed list of supported bitrates. I'm familiar with Dolby Encoding Engine, which lists the following in its documentation:
Code:
32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 128, 144, 160, 176, 192, 200, 208, 216, 224, 232, 240, 248, 256, 272, 288, 304, 320, 336, 352, 368, 384, 400, 448, 512, 576, 640, 704, 768, 832, 896, 960, 1008, 1024, For mono: 32 (minimum), 1024 (maximum) Default: 64 For stereo: 96 (minimum), 1024 (maximum) Default: 128 For 5.1: 192 (minimum), 1024 (maximum) Default: 192 For 7.1: 384, 448, 504, 576, 640, 704, 768, 832, 896, 960, 1008, 1024 Default: 384 |
20th January 2021, 08:03 | #10 | Link | |
SuperVirus
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Quote:
But it sucks that the FOSS encoders may follow the specifications better than the creators of the specifications themselves |
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21st January 2021, 04:18 | #11 | Link |
Derek Prestegard IRL
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Indeed! It may be just to keep QA cycles tighter
It also probably has roots in broadcast hardware encoders where you wouldn't want to "dial-a-bitrate" one Kbps at a time. You want logical steps since you're tapping a button on chassis or twisting a dial. |
4th February 2021, 10:54 | #12 | Link |
Acid fr0g
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Queueing to this opened topic.
I am thinking about starting to convert all the THD/DTSHD tracks in a movie to EAC3 instead of AC3, as I did since some years so far. Given I would anyway convert to 5.1 (FFMPEG limitation) and 640 kbps, should I get some benefits or EAC3 has the same algorithms of AC3 plus just the increase in bitrate and channel numbers? I have been thorougly searching thru the web but no testing has been done AFAIK, especially with FFMPEG instead of commercial encoders.
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4th February 2021, 12:31 | #13 | Link | |
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Quote:
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4th February 2021, 12:49 | #14 | Link |
Acid fr0g
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I have tried to find the possible parameters for eac3 but unsuccessfully. Can you help me?
Again, I've read EBU Evaluations of Multichannel Audio Codecs, where DD at 448 kb/s is comparable to DTS at 1.5 mbit/s. I have read that DD+ is "transparent" to AV receiver, in the way that, if not supported, it is dynamically transcoded to AC3. Is it true?
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@turment on Telegram Last edited by tormento; 4th February 2021 at 12:52. |
4th February 2021, 13:14 | #15 | Link | |
ffx264/ffhevc author
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Quote:
There are no parameters for E-AC-3, except for DRC. You just set it like AC-3 and it does its job. With E-AC-3 you can get the same quality but at lower bitrate than AC-3. I personally encode for years to E-AC-3 5.1 (160 kbps/chan) @ 960 kbps for true transparency. I find higher bitrate doesn't improve things Yes, AVRs that do not support E-AC-3 will on-the-fly transcode it to AC-3. But this depends on the AVR. Some just give an error about not supported audio codec |
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4th February 2021, 13:18 | #16 | Link | |
Acid fr0g
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Quote:
Any problem with passthru bitstream thru optical or HDMI?
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@turment on Telegram Last edited by tormento; 4th February 2021 at 13:20. |
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4th February 2021, 15:49 | #17 | Link |
Pig on the wing
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With TrueHD sources, I'd rather snatch the core AC3 track which is the most compatible and high quality in itself.
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6th February 2021, 12:11 | #19 | Link |
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Are you sure you can - i.e. can you actually ABX the difference between them?
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