There is no such thing as a standard file format for ETI bitstreams. Consequently, you will find a variety of non-compatible ETI files on the market today.

The file format used by CRC is very simple. It is non-padded and can be described as follow:

uint32 nbFrames
for each frame
- uint16 frameSize
- uint8 [frameSize] data
NOTE: Numbers are little-endian

If, for example, you require padded files, you could do this:
1. Read the first 4 bytes to get the number of frames (nbFrames)
2. Read the following 2 bytes to get the frame size (frameSize)
3. Read frameSize bytes of data
4. Write padding to that frame with (6144 - frameSize) bytes with value 0x55
5. Go to step 2 until all frames (nbFrames) have been processed

We could add other formats to our software. Don't hesitate to provide us with your requirements.

Francois.

3 file formats are now supported. We call them framed, streamed and raw.

Framed format is used for file recording. It is the default format. The padding can be removed from data.

Code: :

uint32_t nbFrames for each frame   uint16_t frameSize   uint8_t data[frameSize]

Streamed format is used for streamed applications. As the total number of frames is unknown before end of transmission, the corresponding field is removed. The padding can be removed from data.

Code: :

for each frame   uint16_t frameSize   uint8_t data[frameSize]

Raw format is a bit-by-bit (but byte aligned on sync) recording of a G.703 data stream. The padding is always present.

Code: :

for each frame   uint8_t data[6144]

CRC-DabMod and CRC-EtiStreamer both automatically recognize the input format.

CRC-DabMux uses a file output format option. The format is -O file://filename?type=type. There query part (from ? symbol to the end) is optional. Types are framed, streamed and raw.

Pascal

Please note that our raw format can also be referred to as ETI(NI, G.703) or ETI(NI).

Pascal