Voice compressing in STM32L4

[RFlod.2]

I need to compress voice in STM32L4. Here are my requirements:

* STM32L4 run at maximum 80 MHz

* Voice to be sampled by ADC/DMA

* Flash usage for voice compression < 50 kBytes

* RAM usage for voice compression < 64 kBytes

* Compressed data < 10% of orignal data

* Compress library shall not be GPL (cannot disclose all source code in my project)

* Compressed voice need to be decompressed at Linux OS

So I have searched some libraries and here are my findings:

* ST Opus Cube

- Flash size to big, 163 kBytes

* Speex_STM32_master

- GPL license

* STM32F10x_AN2812_FW_V2.0.0 (speex library)

- Contains assembler files for STM32F1

*  ST X-CUBE-AUDIO

- Only for STM32F4 and STM32F7

So non of these solutions fits my requirements. Any other ideas?

[Danish1]

Stm32F1 and stm32L4 both have arm cortex M processors.

What problems do you get offering the STM32F1 assembly files to an assembler for L4?

[RFlod.2]

STM32F1 uses M3 core

STM32L4 uses M4 core

I do not want to put a lot effort into getting it to work if there is an obvious issue.

[unsigned_char_array]

Opus is BSD licensed. If that works for you you can use a non-ST port/implementation of OPUS.

https://opus-codec.org/license/
https://github.com/xiph/opus

[RFlod.2]

Problem with Opus is the flash size, not the license.

[unsigned_char_array]

Have you tried porting the speex library? What assembler files need to be ported? I can't find the example.

[RFlod.2]

No, I wrote I donot put effort in something that already have issues.

The STM32F1 code is not at ST website, but found it here

https://community.element14.com/products/devtools/technicallibrary/w/documents/24440/stm32f10xxx-speex-library-firmware-stm32---stdperiph-lib---speex---audio

[waclawek.jan]

Cortex-M4 is a superset of Cortex-M3.

JW

[unsigned_char_array]

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@RFlod.2 wrote:

No, I wrote I donot put effort in something that already have issues.

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What issues? Do you get compile errors or doesn't the program operate properly?

Like @waclawek.jan wrote the M4 is a superset of the M3. So inline assembly should work.

If not use C code instead of assembly code. If that doesn't perform enough you can try to see if you can use CMSIS DSP library: https://github.com/ARM-software/CMSIS-DSP

[RFlod.2]

It wil take time to implement and verify this implementation.. It would be preferable to use an existing working solution.

Debugging assembler is something I would like to avoid. Even though the core might be compatible there can be callls to other oarthe in the STM32 which are not compatible.