Re: [Freetel-codec2] Updating the libcodec2 binding in FFmpeg, fixed-point decoding
I would think, that a floating pt implementation on a soft FPGA processor core with floating point would take less area that a purely FPGA fixed point HDL implementation. The reason is that the amount of work required to do (in terms of computations per cycle) does not really take advantage of the parallelism of an FPGA . and a basic soft core with an FPU can easily run fast enough on even the slowest FPGA fabric around However, I suspect that codec2 could easily work within small fractional integer space (32 to 40 bit) without changes, and not have any scaling issues and be completely scaling free in a 64 bit fractional integer space. My usual rule - if it can be run in a high level language in software, then don't do it in fpga fabric as HDL ... probably applies. I'm currently implementing codec2 for RISC-V (F) in floating point. In many RISC-V implementations, there is the facility to generate in the HDL custom instructions that can be inserted into the code which can provide , for example, vector speedups. In my opinion, There's a good reason though not to go too far from 'reference C code' if possible, unless, for example there are struct power consumption limits- as changes to the mainline become slower and more difficult to propagate into different platforms if someone needs to spend the time to (heavily) optimize. If the use of fixed point requires regular scaling, it probably becomes a pain to be linked to the mainline reference code unless the scaling requirements are scripted and automatic. This breathes light for me into thinking about a purely 64bit fractional ALU fractional implementation. In the RISCV -custom instruction support , one could add fractional ALU instructions that MACRO out the std asm to hide the shifts from the programmer and compiler. -glen On 28/12/2023 7:36 am, Mooneer Salem wrote: Hi Tomas, Someone did a FPGA implementation a while back for a university project. That's the closest we've gotten to a fixed-point implementation. Right now, there are no plans to port it officially but this may be revisited later. Thanks, -Mooneer K6AQ ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
Re: [Freetel-codec2] Updating the libcodec2 binding in FFmpeg, fixed-point decoding
Hi Tomas, Thanks for that work. 1.2 was clean up of the Git repo, so nothing much has changed in terms of functionality. We have no plans for a fixed point version. The .c2 file format is a corner use-case (we focus mainly on the HF radio use case), but we have no plans to change it. A road map of what is currently placed for the entire FreeDV project (which includes Codec 2) is here: https://freedv.org/2023/11/30/ardc-grant-project-plan/ Do you have any way of measuring how many people are using the Codec 2 option in FFmpeg? We have been looking into the use of the freedv-gui application (which uses libcodec2) in various repos and found no evidence of the packaged versions of freedv-gui actually being used. The number of package maintainers seems to to outnumber the end users. We are interested in auditing the use of freedv-gui and Codec 2 to best direct our efforts. For example there is no point supporting package maintainers if no one is using the packages - best to direct our limited resources elsewhere. I find it interesting that package maintenance is such a popular hobby - we get more correspondence/requests for help on this topic than say the DSP side of Codec 2 (where I like to play). Thanks, David On Wed, 2023-12-27 at 18:48 +0100, Tomas Härdin wrote: > Hi > > I see codec2 has now reached version 1.2.0. I'm working on updating > the > libcodec2 binding in libavformat in FFmpeg accordingly. > > So far I've been conservative, only allowing major version 0 and > requiring version to be >= 0.8. So in effect versions 0.8 to 0.255. > Now > that 1.X is out I'm updating libavformat accordingly. Fortunately the > .c2 format hasn't changed, so this is more of a heads up to be > careful > not to make breaking changes to the format :) > > In effect what I'm doing is allowing versions 0.8 through 1.255. > > I'm also adding tests to FFmpeg's testing system FATE. So far these > tests are quite basic, only checking metadata rather than the actual > decoded audio. This because libcodec2 uses floating point arithmetic. > At some time I'd like to improve that. Are there any plans to > implement > a fixed-point decoder? I remember seeing some chatter about that. > > /Tomas > > > ___ > Freetel-codec2 mailing list > Freetel-codec2@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
Re: [Freetel-codec2] Updating the libcodec2 binding in FFmpeg, fixed-point decoding
Hi Tomas, Someone did a FPGA implementation a while back for a university project. That's the closest we've gotten to a fixed-point implementation. Right now, there are no plans to port it officially but this may be revisited later. Thanks, -Mooneer K6AQ On Wed, Dec 27, 2023 at 10:11 AM Tomas Härdin wrote: > Hi > > I see codec2 has now reached version 1.2.0. I'm working on updating the > libcodec2 binding in libavformat in FFmpeg accordingly. > > So far I've been conservative, only allowing major version 0 and > requiring version to be >= 0.8. So in effect versions 0.8 to 0.255. Now > that 1.X is out I'm updating libavformat accordingly. Fortunately the > .c2 format hasn't changed, so this is more of a heads up to be careful > not to make breaking changes to the format :) > > In effect what I'm doing is allowing versions 0.8 through 1.255. > > I'm also adding tests to FFmpeg's testing system FATE. So far these > tests are quite basic, only checking metadata rather than the actual > decoded audio. This because libcodec2 uses floating point arithmetic. > At some time I'd like to improve that. Are there any plans to implement > a fixed-point decoder? I remember seeing some chatter about that. > > /Tomas > > > ___ > Freetel-codec2 mailing list > Freetel-codec2@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/freetel-codec2 > ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
[Freetel-codec2] Updating the libcodec2 binding in FFmpeg, fixed-point decoding
Hi I see codec2 has now reached version 1.2.0. I'm working on updating the libcodec2 binding in libavformat in FFmpeg accordingly. So far I've been conservative, only allowing major version 0 and requiring version to be >= 0.8. So in effect versions 0.8 to 0.255. Now that 1.X is out I'm updating libavformat accordingly. Fortunately the .c2 format hasn't changed, so this is more of a heads up to be careful not to make breaking changes to the format :) In effect what I'm doing is allowing versions 0.8 through 1.255. I'm also adding tests to FFmpeg's testing system FATE. So far these tests are quite basic, only checking metadata rather than the actual decoded audio. This because libcodec2 uses floating point arithmetic. At some time I'd like to improve that. Are there any plans to implement a fixed-point decoder? I remember seeing some chatter about that. /Tomas ___ Freetel-codec2 mailing list Freetel-codec2@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freetel-codec2
