VolcEngine RTC (OTA A/B Partition) Solution DEMO Development Guide

[中文]

1 Project Overview

This project adds OTA A/B dual-partition upgrade capability on top of the `volc_rtc <../volc_rtc/README.md>`_ project. The basic real-time audio/video communication, audio processing, AI Agent integration, room management, and other features are identical to volc_rtc. This document focuses only on the OTA A/B partition differences; for all other features, please refer directly to the volc_rtc project documentation:

> In short: ``volc_rtc_ab`` = all features of ``volc_rtc`` + OTA A/B partition upgrade.

2 OTA A/B Upgrade Introduction

2.1 What is OTA A/B

The basic idea of OTA A/B (dual-partition) upgrade: Flash keeps two firmware partitions; the device runs from the current partition, and during OTA the new firmware is written into the other (standby) partition, after which the boot partition is switched to complete the upgrade. Compared with a single firmware partition scheme, one firmware copy is always kept during the upgrade, at the cost of more Flash space.

> Note: The exact behavior of boot-partition switching, verification, and rollback is determined by the bootloader and the SMP SDK OTA mechanism—please refer to the SMP OTA documentation. The difference between this project and volc_rtc is limited to the partition table and packaging configuration described below.

2.2 Partition Layout Differences

The core difference between volc_rtc_ab and volc_rtc lies in the partition table partitions/bk7258/auto_partitions.csv. The values and read/write attributes below are taken directly from that file in both projects:

Partition | volc_rtc (single) | volc_rtc_ab (A/B) | Description |
— | — | — | — |
primary_bootloader | 68k | 68k | Bootloader |
primary_cp_app | 1428k (Write=FALSE) | 1360k (Write=TRUE) | CP-core firmware partition; attribute changed from read-only to writable in the A/B project |
primary_ap_app | 2992k (Write=FALSE) | 2652k (Write=TRUE) | AP-core firmware partition; attribute changed from read-only to writable in the A/B project |
ota | 3128K | none | OTA partition of the single-partition scheme |
s_app | none | 4012k | Partition added by the A/B project; annotated as “B partition” (standby firmware partition) in the partition table |
ota_fina_executive | none | 4K | Partition added by the A/B project; refer to the SMP OTA documentation for its purpose |
usr_config | 60K | 56K | User configuration partition |

Key points (all verifiable in the partition table): s_app is a partition added by the A/B project, explicitly annotated as “B partition”; the write attribute of primary_cp_app / primary_ap_app is changed from FALSE to TRUE.

2.3 A/B Position-Independent Upgrade

The project adds partitions/bk7258/ab_position_independent.csv:

pos_independent,TRUE

When pos_independent is TRUE, the A/B position-independent upgrade feature is enabled; set it to False if the feature is not needed (see the comment inside the file). Please refer to the SMP OTA documentation for the concrete implementation and limitations of this feature.

2.4 OTA Upgrade Package (RBL) Configuration

The project adds partitions/bk7258/ota_rbl.config, used to generate the A/B upgrade package app_packab.rbl:

{
    "key":"0123456789ABCDEF0123456789ABCDEH",
    "iv":"0123456789ABCDEF",
    "gzip":"0",
    "aes":"0",
    "outf":"app_packab.rbl"
}

Field meanings (refer to the SMP rbl packaging tool documentation):

  • key / iv: the key and initialization vector used for upgrade-package encryption/decryption;

  • aes: whether the upgrade package is AES-encrypted (0 / 1);

  • gzip: whether the upgrade package is compressed (0 / 1);

  • outf: output upgrade package file name (here app_packab.rbl).

> ⚠️ It is recommended to replace the example key / iv with your project’s own secure keys before mass production.

3 Quick Start

3.1 Compilation and Flashing

Compilation process reference: AI Solution. Replace the project path in the commands with projects/volc_rtc_ab.

Compilation command example:

cd ~/armino/bk_solution_ai/projects/volc_rtc_ab
export SDK_DIR=~/armino/bk_avdk_smp
make clean
make bk7258

Full firmware (for the initial full flash; path naming follows volc_rtc): projects/volc_rtc_ab/build/bk7258/volc_rtc_ab/package/all-app.bin

A/B OTA upgrade package: the file name is defined by outf in ota_rbl.config, i.e. app_packab.rbl.

Flashing process reference: SMP flashing procedures.

3.2 Upgrade Flow

  1. Flash all-app.bin with the flashing tool for the first time;

  2. For subsequent versions, push the A/B upgrade package app_packab.rbl via the OTA channel to complete the upgrade.

> For the concrete OTA flow and interfaces (download, write, verification, and partition switching), please refer to the SMP OTA documentation.

4 API Reference

The RTC / Agent / audio-video sending APIs of this project are identical to volc_rtc. Please refer to: