format/flac/flac_streaminfo.go

package flac

import (
	"github.com/wader/fq/format"
	"github.com/wader/fq/pkg/decode"
	"github.com/wader/fq/pkg/interp"
	"github.com/wader/fq/pkg/scalar"
)

func init() {
	interp.RegisterFormat(
		format.FLAC_Streaminfo,
		&decode.Format{
			Description: "FLAC streaminfo",
			DecodeFn:    streaminfoDecode,
		})
}

func streaminfoDecode(d *decode.D) any {
	d.FieldU16("minimum_block_size")
	d.FieldU16("maximum_block_size")
	d.FieldU24("minimum_frame_size")
	d.FieldU24("maximum_frame_size")
	sampleRate := d.FieldU("sample_rate", 20)
	// <3> (number of channels)-1. FLAC supports from 1 to 8 channels
	d.FieldU3("channels", scalar.UintActualAdd(1))
	// <5> (bits per sample)-1. FLAC supports from 4 to 32 bits per sample. Currently the reference encoder and decoders only support up to 24 bits per sample.
	bitsPerSample := d.FieldU5("bits_per_sample", scalar.UintActualAdd(1))
	totalSamplesInStream := d.FieldU("total_samples_in_stream", 36)
	md5BR := d.FieldRawLen("md5", 16*8, scalar.RawHex)
	md5b := d.ReadAllBits(md5BR)

	return format.FLAC_Streaminfo_Out{
		StreamInfo: format.FLAC_Stream_Info{
			SampleRate:           sampleRate,
			BitsPerSample:        bitsPerSample,
			TotalSamplesInStream: totalSamplesInStream,
			MD5:                  md5b,
		},
	}
}