detectImageMimeType function

String detectImageMimeType(
  1. Uint8List bytes
)

sniffEncodedMediaFormat's MIME type for an IMAGE, else 'image/png' — the fallback the LLM web arms have always used for bytes they could not identify. Audio bytes get the fallback too: this answers "what kind of image is this", and has never named an audio type.

Implementation

String detectImageMimeType(Uint8List bytes) {
  final format = sniffEncodedMediaFormat(bytes);
  return format != null && format.modality == EmbeddingModality.image
      ? format.mimeType
      : EncodedMediaFormat.png.mimeType;
}