Ecasound Support for Apple AIFF and AIFC Files

Ecasound fully supports reading and writing both Apple AIFF and AIFC audio files, primarily through its integration with the libsndfile library. This article outlines how Ecasound handles these formats, the dependencies required to enable support, and how to execute standard read and write operations via the command line.

How Ecasound Handles AIFF and AIFC

Ecasound relies on external audio libraries rather than maintaining separate, internal decoders for every file container. For standard container formats like AIFF (Audio Interchange File Format) and AIFC (AIFF-C, or compressed AIFF), Ecasound utilizes libsndfile or the legacy audiofile library.

Because libsndfile natively supports reading and writing AIFF and AIFC, Ecasound inherits full compatibility with both formats as long as it was compiled with libsndfile support enabled (which is the default on virtually all modern Linux distributions and package managers).

Reading AIFF and AIFC Files

To read an AIFF or AIFC file, specify it as an input source using the -i option. Ecasound automatically detects the container type and audio parameters (such as sample rate, bit depth, and channel count) from the file header.

Standard AIFF input:
```
ecasound -i input.aiff -o alsa
```
AIFC input:
```
ecasound -i input.aifc -o alsa
```

You can also explicitly specify the sndfile engine if file extensions are non-standard:

ecasound -i sndfile,input.audio -o alsa

Writing AIFF and AIFC Files

To write to an AIFF or AIFC container, define the target with the -o parameter using the appropriate file extension. Ecasound instructs the underlying library to construct the proper header format.

Rendering to AIFF:
```
ecasound -i input.wav -o output.aiff
```
Rendering to AIFC:
```
ecasound -i input.wav -o output.aifc
```

If needed, you can define target audio parameters (such as 24-bit linear PCM, 48 kHz, stereo) using the -f flag prior to defining the output file:

ecasound -i input.wav -f:s24_be,2,48000 -o output.aiff

(Note: Big-endian formats like s16_be or s24_be represent traditional standard AIFF formatting, while little-endian formats like s16_le are typically encapsulated within AIFC via the 'sowt' compression type).

Compression and Codec Limitations with AIFC

While uncompressed linear PCM in both AIFF and AIFC is universally supported, AIFC can theoretically contain various compressed streams (such as GSM, IMA ADPCM, or legacy Apple codecs). Ecasound can only read or write these streams if the underlying libsndfile binary supports the specific compression algorithm. Standard PCM, floating-point formats, A-law, and u-law encodings within AIFC containers are fully supported.