SDS File

Files with the SDS extension contain a MIDI data dump in the SDS - Sample Dump Standard format. These are raw, uncompressed data, which means their size can be significantly larger than the actual sound wave recordings. The sounds can range from 8 to 32 bits, in mono mode. The SDS format is considered obsolete and is generally no longer used.

Writing data in an SDS file

The SDS format was developed to facilitate the exchange of data between MIDI devices and is based on this standard. The following SysEx - standardized System Exclusive messages are used to write in the SDS files:

• dump request - a dump request sent by the recipient,
• dump header - a dump header created by the sender,
• dump data - a MIDI data dump from the sender,
• ACK - transmission confirmation,
• NAK - a message informing of failure,
• CANCEL - a request to end the transmission, cancellation,
• WAIT - a request to wait until the attempt to transmit is repeated.

When transmitting, the data is divided into packets, each containing up to 120 bytes. The total length of a single packet is 127 bytes. A dump type file contains both data packets and messages sent by the transmitter.

Handling SDS files through MIDI devices

Dumps to SDS files can be performed from hardware devices or audio programs. This format is supported by various hardware and software samplers. Many of them, besides playing, also allow for editing the data. Such software also makes it possible to convert to popular sound formats.