Ambe Codec Softwares
AMBE is a codebook-based vocoder that operates at bitrates of between 2 and 9.6 kbit/s, and at a sampling rate of. Feb 27, 2018 - AMBE is a codebook-based vocoder that operates at bitrates of between 2 and 9.6 kbit/s. DVSI does not disclose software licensing terms. Sounds like they were jealous of the DV Dongle, and so decided to 'one up. Digital Voice Systems Inc.' S Vocoder Chips provide implementations of the standard-setting AMBE®, AMBE+™ or AMBE+2™ voice compression technologies. DVSI's patented AMBE® voice compression software has been proven to outperform CELP, RELP, VSELP, MELP, ECELP, MP-MLQ, LPC-10, and other competitive technologies. Because Speex is a waveform codec and AMBE is a vocoder, we can expect Speex to improve intelligibility somewhat. Jean-Marc Valin, one of the Speex developers, proposed these steps: Making the bit-stream more robust by adding Gray coding, index assignment, and so on.
Ambe Codec Softwares Windows 7
Yesterday I was chatting on the #freedv IRC channel, and a good question was asked: how close is to AMBE+2? Turns out – reasonably close.
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I also discovered, much to my surprise, that Codec 2 700C is better than MELPe 600!Samples OriginalAMBE+2 3000AMBE+ 2400Codec 2 3200Codec 2 2400OriginalMELPe 600Codec 2 700CHere are in one big tar ball.DiscussionI don’t have a AMBE or MELPe codec handy so I used the samples from the and web sites. I passed the original “DAMA” speech samples found on these sites through Codec 2 (codec2-dev SVN revision 3053) at various bit rates. Turns out the DAMA samples were the same for the AMBE and MELPe samples which was handy.These particular samples are “kind” to codecs – I consistently get good results with them when I test with Codec 2. I’m guessing they also allow other codecs to be favorably demonstrated. During Codec 2 development I make a point of using “pathological” samples such as hts1a, cgref, kristoff, mmt1 that tend to break Codec 2. Some samples of AMBE and MELP using my samples on the page.I usually listen to samples through a laptop speaker, as I figure it’s close to the “use case” of a PTT radio.
Small speakers do mask codec artifacts, making them sound better. I also tried a powered loud speaker with the samples above. Through the loudspeaker I can hear AMBE reproducing the pitch fundamental – a bass note that can be heard on some males (e.g. 7), whereas Codec 2 is filtering that out.I feel AMBE is a little better, Codec 2 is a bit clicky or impulsive (e.g. On sample 1).
However it’s not far behind. In a digital radio application, with a small speaker and some acoustic noise about – I feel the casual listener wouldn’t discern much difference. Try replaying these samples through your smart-phone’s browser at an airport and let me know if you can tell them apart!On the other hand, I think Codec 2 700C sounds better than MELPe 600. Codec 2 700C is more natural. To my ear MELPe has very coarse quantisation of the pitch, hence the “Mr Roboto” sing-song pitch jumps.
The 700C level is a bit low, an artifact/bug to do with the post filter. Must fix that some time. As a bonus Codec 2 700C also has lower algorithmic delay, around 40ms compared to MELPe 600’s 90ms.Curiously, Codec 2 uses just 1 voicing bit which means either voiced or unvoiced excitation in each frame.
XMBE’s claim to fame (and indeed MELP) over simpler vocoders is the use of mixed excitation. Some of the spectrum is voiced (regular pitch harmonics), some unvoiced (noise like). This suggests the benefits of mixed excitation need to be re-examined.I haven’t finished developing Codec 2. In particular Codec 2 700C is very much a “first pass”. We’ve had a big breakthrough this year with 700C and development will continue, with benefits trickling up to other modes.However the 1300, 2400, 3200 modes have been stable for years and will continue to be supported.Next StepsHere is the that kicked off Codec 2 – way back in 2009.
Here is a that explains the motivations, IP issues around codecs, and a little about how Codec 2 works (slides ).What I spoke about then is still true. Codec patents and license fees are a useless tax on business and stifle innovation. Proprietary codecs borrow as much as 95% of their algorithms from the public domain – which are then sold back to you. I have shown that open source codecs can meet and even exceed the performance of closed source codecs.Wikipedia suggests that AMBE license fees range from. For “one license fee” we can improve Codec 2 so it matches AMBE+2 in quality at 2400 and 3000 bit/s. The results will be released under the LGPL for anyone to use, modify, improve, and inspect at zero cost.
Forever.Maybe we should crowd source such a project?Command LinesThis is how I generated the Codec 2 wave files:/codec2-dev/buildlinux//src/c2enc 3200 9.wav - /codec2-dev/buildlinux/src/c2dec 3200 - sox -t raw -r 8000 -s -2 - 9codec23200.wavLinks, MELPe samples. Can anyone provide me with TWELP samples from these guys? I couldn’t find any on the web that includes the input, uncoded source samples. Posted on Author Categories.
I have been confronted with ambe+2 for many years at my 2 previous jobs (inmarsat i4 voice in particular) and we always admired how it fit the bill for this purpose. In the typical, noisy environment inside aircrafts (also in the cargo while on ground, doors open, APU, GPU, hydraulics etc. Running during maintenance) this codec sounded awesome. Even if compared to the i3’s g711 (Swift64 ISDN) not to mention iridium and worst inmarsat classic aero voice (both IMBE?).
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We always suspected that ambe+2 was great at filtering out noise and encoding just voiced parts of the source signal. Widi 4 0 keygen free download. But had no real insight (you heard of IP rights??) Voice sounded slightly robotised but it was no problem identifying the speaker. One thing we found out to throw over its superiour intellegibility was using DECT handsets as an input source, g711 ISDN desk phones were fine.There was one funny episode while discussing with our supplier for PBX systems about qualities of ambe and their preffered GSM FR codec, when their sales rep said why dont we just license AMBE then??? You know the rumours about fees 😉Even my post is not very technical, i hope it gets you a feeling where AMBE+2 shines (at presumably 2400bps).Unfortunately I’m no more having access to SATCOM terminals for tests with codec2. But I’m pretty convinced that preprocessing of the signal is most important, and if this is upset by eg. DECT’s ADPCM the codecs intelligibility falls apart.I hope codec2 will surpass ambe and make it(‘s business model) obsolete.Thanks for your time and efforts developping the algorithms and keeping a community alive here. Hi David, I love to tell stories of the good old times in aviation 😉I’m loosly following your progress since i got to know about codec2 and am impressed by your persistence and your way of dealing with new problems, also outside of your field.I have just one random OT question, which I think you might be able to answer.
If not never mindHave you ever heard of a real world use of TCM (no not chineese medicine, trellis coded modulation) I always found the concept interesting, but never found any trace of it outside of academia.Is it too “costly” to implement or impractical or is it just obsolete due to better alternatives?.