pion/opus

Pure Go implementation of Opus

opus's Issues

Implement the Opus Packet parsing

• #8
• Parse the packet information
• Parse the opus compressed frame information

Implement resampling the SILK audio to the CELT sample rate.

Support Silk frames without 4 subframes

Currently we are hardcoded to expect 4 subframes (20Ms)

We need to go through and fix the cases where we do that.

unsupported configuration mode: 2

Trying to decode Telegram voice messages, get unsupported configuration mode: 2

Sample file:
https://file.io/LAv06s4gaw1o

Implement CELT

• Implement the rawbits/reverse bitreader
• Implement the other symbol reading methods
• Implement the fixed maths routines (isqrt)
• ...

Implement SILK

• #5
• Implement the Opus compressed frame parsing (SILK)
• Implement the SILK frame parsing
  • Implement Stereo support
  • Implement the SILK subframe parsing
  • Write down all the lookup tables required and doublecheck them
  • Parse all the codec parameters and make sure you do for each bandwidth
• Implement the unmixing/channel copy for the stereo/mono support.

NOTE: Low Bitrate Redundancy frames are low priority for on-disk opus but you will need to support/skip them in the webrtc context.

Finish limitLPCFilterPredictionGain described in section-4.2.7.5.7

Currently none of it is implemented

Add Opus Test Vectors to CI

Playback example module contains replace directive

opus/examples/playback/README.md

Line 9 in 70baa27

go install github.com/pion/opus/examples/playback@latest

Running this command produces an error message:

go: github.com/pion/opus/examples/playback@latest (in github.com/pion/opus/examples/[email protected]):
	The go.mod file for the module providing named packages contains one or
	more replace directives. It must not contain directives that would cause
	it to be interpreted differently than if it were the main module.

Wasm based decode example

In a web worker , this would make it easy to build various apps that need sound

in a server , mobile iot desktop you can do the same with Wazero with no cgo also.

Encode too ?

Question: this is a decoder only ?

no plans to also encode ?

Is there a plan to support pcm->opus encoding?

Summary

If I understand correctly, pion opus only support decoding operations, is there any plan to support encoding operations in the future?

Motivation

I've written a streaming-WebRTC gateway app that can convert av streams from streaming devices to WebRTC via pion, but now there's a tricky problem, the audio encoding provided by these media devices is usually aac (or can be set to pcm, which is configurable on the device), I can't find a library that implements pcm -> opus in pure go, only some library based on c-go (like this one). The c-go based library has some limitations (e.g. it can't be self-contained), so it would be nice if pion opus supported pcm->opus.

Describe alternatives you've considered

.

Additional context

.

Opus implementation tracker

• Implement SILK #3
• #7
• #6

Enable Pion .goassets

Sets up all the testing and linters

Implement normalizeLSFStabilization

Currently a noop

Defined in https://datatracker.ietf.org/doc/html/rfc6716#section-4.2.7.5.4

Implement the RangeCoder

• Implement/use a bitstream reader
• Implement/use a reverse bitstream reader
• Implement the actual RangeCoder

LICENSE file missing

README.md links to https://github.com/pion/opus/blob/master/LICENSE, however, LICENSE file does not exist.

Opus packet parsing

• Implement/use a bitstream reader
• Implement/use a reverse bitstream reader
• Implement the RangeCoder
• Parse the packet information
• Parse the opus compressed frame information

Range Decoder

Extract the ec_ctx from libopus and write tests against it. Write a Go idiomatic version that passes all the same tests

Configuration mode should include 0 as SilkOnly mode

Your environment.

• Version: 6520e40

Hello!
I was looking at table_of_contents_header.go, and noticed that the Configuration.mode() method returns 0 if c = 0.
According to RFC6716, if c = 0, it should be determined to be in SILKOnly mode.
Can I fix it?

`ParseNextPage()` in oggreader.go does not handle OPUS packets that span multiple segments

Your environment.

• Version: master

What did you do?

Decoding SILK OGG OPUS streams and some of them are changing from to CELT codec after some time and thus failing.

What did you expect?

Proper decoding of the of the whole SILK encoded stream

What happened?

oggreader returned error that CELT is not supported

Fix

The problem is in the loop that is reading the segments. It does not handle the case if the segment's length is 255, which means that the OPUS packet spans multiple segments

opus/pkg/oggreader/oggreader.go

Line 157 in 8667a1a

for _, s := range sizeBuffer {

Pseudo code of the correct loop can be found at https://gist.github.com/amishshah/68548e803c3208566e36e55fe1618e1c

Implementing something similar in my own, heavily modified oggreader, solved all the decoding problems.

Implement relative lag is Silk Decoder

Currently we only process correctly if lagAbsolute is true.

https://github.com/pion/opus/blob/master/internal/silk/decoder.go#L1118

Support Stereo frames in Silk

Roadmap

This is a covering ticket for the Pion Opus roadmap. If you have any requests feel free to leave them here/vote on others.

0.0.1

• SILK Decoder
• CELT Decoder

0.0.2

• SILK Encoder
• CELT Encoder