Құрылғылар үшін баламалық микропрограммалық жасақтама: Rockbox

Firmware replacement for various devices
the Run–D. M. C. song

Rockbox is a free and open source software replacement for the OEM firmware in various forms of digital audio players (DAPs) with an original kernel. It offers an alternative to the player's operating system, in many cases without removing the original firmware, which provides a plug in architecture for adding various enhancements and functions. Enhancements include personal digital assistant (PDA) functions, applications, utilities, and games. Rockbox can also retrofit video playback functions on players first released in mid 2000. Rockbox includes a voice driven user interface suitable for operation by visually impaired users. Rockbox runs on a wide variety of devices with very different hardware abilities: from early Archos players with 1 bit character cell based displays, to modern players with high resolution color displays, digital optical audio hardware and advanced recording abilities.

The Rockbox project began in late 2001 and was first implemented on the early Archos series of hard disk based MP3 players/recorders (including the flash only model Ondio), because of owner frustration with severe limitations in the manufacturer supplied user interface and device operations. These devices have relatively weak main central processing units (CPU), and instead offload music playback to dedicated hardware MP3 decoding chips (MAS). Rockbox was unable to significantly alter playback abilities. Instead, it offered a greatly improved user interface and added plug in functions absent in the factory firmware. Rockbox can be permanently flashed into flash memory on the Archos devices, making it a firmware replacement. Versions of Rockbox have since been produced for more sophisticated devices. These perform audio decoding in software, allowing Rockbox to potentially support many more music formats than the original firmware, and adding the extensibility and increased functions already present in the Archos ports. Rockbox is run from the hard drive or flash memory after being started with a custom boot loader, so to upgrade Rockbox, users need only copy the files onto the player's drive and restart the device. Reflashing is only needed when changing the boot loader, and on some platforms is not needed at all. The first of these ports, beginning in late 2004, was for the ColdFire powered devices manufactured by iriver, focusing on the H1xx series of hard drive players (H110/H120/H140). About one year later, a port for the H3xx series became functional, offering similar functions. Additionally builds are often available to developers of unsupported targets, which, while somewhat functional, are typically not ready for general users due to incomplete features or poor stability. As of 2021, there have been no new ports released.

Subject to the limitations of each particular platform, the appearance of Rockbox can be customised in various ways. Fonts and foreground and background colours can be added and selected, while a simple markup language can be used to create themes for the menu and playback screens. These themes can include backgrounds and other images (such as icons), plus various formats for file names, ID3 tags, album art, file progress, and time and system information. Rockbox has essentially been a file tree based player, to which folders could be dragged and dropped and then navigated by folder structure. However, more recent versions have included a complementary database feature which allows the player to compile information from the files' ID3 tags. The user can then navigate the files regardless of file structure.

Rockbox has many features additional to those supported by the original operating firmware, but in many cases there are limitations. On platforms classified as "stable" and supported, the device can be used as a digital music player, but even on some such platforms Rockbox does not support charging or USB; the player must be dual booted into the original firmware to be charged or to transfer files. Some platforms are classified as "unstable", but supported; those deemed "unusable" are not supported, and their use is not recommended. Some porting projects are in a pre development hunting and gathering stage, with no code written.

Rockbox on software decoding platforms (non Archos) supports playback of twelve lossy codecs (depending on how one counts), five lossless, two uncompressed and twelve miscellaneous formats. This makes a conservative total of 30 supported audio formats, although a few of them do not operate in realtime on all platforms. Extensive work has gone into optimizing each codec, with FLAC, Ogg Vorbis, WMA, APE, TTA, MPC, Wavpack, ATRAC3, Cook and WMA Pro among the fastest known integer implementations for those formats.

In addition, there are playback of game audio types ADX, SID, NSF, SAP, SPC, AY, GBS, HES, KSS, SGC, VGM, and VGZ. The MOD tracker format, and the Yamaha SMAF are also now supported. Some profiles in Monkey's Audio are not real time on all targets due to very high CPU needs. Also, Rockbox will not play files with a digital rights management (DRM) scheme.

Rockbox uses a simple kernel, with a flat memory model and single process, letting it run on platforms without a memory management unit. Thin threads run cooperatively, returning control to a scheduler that prioritizes the audio thread; the only form of preemption is through interrupts. The operating system and plug ins are written in C, with assembly used for code that is device and platform specific, and performance sensitive. The simple and lightweight architecture allows Rockbox to run on a variety of targets, with memory ranging from 1 to 64 MB, and CPU speeds ranging 12 to 532 MHz. Rockbox also provides support for multicore and asymmetric multiprocessor systems based on ARM, ColdFire, MIPS and SH. Several codecs can be parallelized across 2 CPU cores for increased power efficiency, and the HWCODEC interface allows for dedicated audio decoder DSPs.

The Rockbox Utility is a free computer application, available for Linux, Mac OS X, and Microsoft Windows, built using Digia Qt platform, that is used to install and manage Rockbox on DAPs. Rockbox Utility provides automatic installation of Rockbox, as well as themes and voice files, directly onto a DAP with minimal user interaction. Rockbox Utility is updated frequently as support for new devices is added.