## evs_decoder.png

The image is a detailed block diagram labeled "Decoder Block Diagram." It illustrates the process of decoding audio data into an output audio signal. The diagram is divided into several sections, each representing different stages in the decoding process.

### Left Section: Jitter Buffer Management (IBM)
- **Bitstream**: This section starts with the input bitstream.
- **Jitter Buffer Management (IBM)**: This part manages the jitter buffer to ensure smooth playback of audio data. It is crucial for maintaining consistent timing and preventing audio dropouts or distortion due to variations in network latency.

### Middle Section: Decoder
This section details the core decoding process, which includes different modes supported by the decoder:

- **EVS PRIMARY MODES**:
  - **LP-based decoder**: This uses a low-pass filter approach.
  - **MDCT-based decoder**: Uses Modified Discrete Cosine Transform for better frequency resolution and lower computational complexity.
  - **BWE decoder**: Bandwidth extension decoder, which enhances the quality of the decoded audio by adding missing frequencies.

- **AMR-WB BACKWARD COMPATIBLE MODE**:
  - **DTX, CNG decoder**: Discontinuous transmission mode (DTX) and Context-Dependent Noise Generation (CNG).
  - **AMR-WB IO decoder**: Interoperable Object (IO) mode for AMR-WB codec.

### Right Section: Post-processing
This section describes the post-processing steps that refine the decoded audio to improve its quality:

1. **Music enhancer**:
   - Enhances the music content in the audio signal.
2. **UV/inactive post-processing**: Processes silent or inactive parts of the audio, ensuring smooth transitions and reducing artifacts.
3. **Comfort noise addition**: Adds a level of comfort noise to ensure that there is no silence perceived by the listener when the speaker is not talking.
4. **Bass post-filter**: Enhances bass frequencies for better sound quality.
5. **Formant noise addition**: Adjusts formants (vowel sounds) in the audio signal, improving clarity and naturalness of speech.
6. **Comfort noise addition** (repeated): Ensures that there is no silence perceived by the listener when the speaker is not talking.
7. **Bass post-filter**: Enhances bass frequencies for better sound quality.
8. **Formant post-filter**: Adjusts formants in the audio signal, improving clarity and naturalness of speech.
9. **De-emphasis**: Reduces high-frequency noise to improve the overall quality of the audio.
10. **Filter-bank & resampling**: Processes the audio through a filter bank for better frequency analysis and then resamples it to match the desired output format.
11. **HP filter**: High-pass filter, which removes low-frequency components that are not needed in the final output.

### Output: Output Audio
The final stage of the diagram shows the "Output audio," which is the processed and enhanced version of the original input bitstream, ready for playback or further use.

### Logos at the Bottom:
- **Ericsson**: A telecommunications company.
- **Fraunhofer**: A German research organization known for its contributions to technology development.
- **HUAWEI**: A Chinese multinational information and communication technology company.
- **VoiceAge**: Likely a company specializing in voice-related technologies.

The diagram is sourced from the AES (Audio Engineering Society) website, with the specific document ID provided.

This description was generated automatically from image files by a local LLM, and thus, may not be fully accurate. Please feel free to ask questions if you have further questions about the nature of the image or its meaning within the presentation.