title: Audio can not find value["bytes"]
comments: ![image](https://user-images.githubusercontent.com/34292279/168063684-fff5c12a-8b1e-4c65-b18b-36100ab8a1af.png)
  
  that is reason my bytes`s empty
  but i have some confused why path prior is higher than bytes?
  
  if you can make bytes in _generate_examples , you don`t have to make bytes to path?
  because we have path and bytes already > but i have some confused why path prior is higher than bytes?
  
  If the audio file is already available locally, we don't need to store the bytes again.
  
  If you don't specify a "path" to a local file, then the bytes are stored. You can set "path" to None for example.
  
  > if you can make bytes in _generate_examples , you don`t have to make bytes to path?
  > because we have path and bytes already
  
  It's useful to pass both "path" and "bytes" in `_generate_examples`:
  - when the dataset has been downloaded, then the "path" to the audio files are stored and we can ignore "bytes" in order to save disk space.
  - when the dataset is loaded in streaming mode, the audio files are not available on your disk and therefore we use the "bytes" 
body: ## Describe the bug
  I wrote down _generate_examples like:
  ![image](https://user-images.githubusercontent.com/34292279/168027186-2fe8b255-2cd8-4b9b-ab1e-8d5a7182979b.png)
  
  but where is the bytes?
  ![image](https://user-images.githubusercontent.com/34292279/168027330-f2496dd0-1d99-464c-b15c-bc57eee0415a.png)
  
  
  ## Expected results
  value["bytes"] is not None, so i can make datasets with bytes, not path
  
  ## bytes looks like:
  blah blah~~
  \xfe\x03\x00\xfb\x06\x1c\x0bo\x074\x03\xaf\x01\x13\x04\xbc\x06\x8c\x05y\x05,\t7\x08\xaf\x03\xc0\xfe\xe8\xfc\x94\xfe\xb7\xfd\xea\xfa\xd5\xf9$\xf9>\xf9\x1f\xf8\r\xf5F\xf49\xf4\xda\xf5-\xf8\n\xf8k\xf8\x07\xfb\x18\xfd\xd9\xfdv\xfd"\xfe\xcc\x01\x1c\x04\x08\x04@\x04{\x06^\tf\t\x1e\x07\x8b\x06\x02\x08\x13\t\x07\x08 \x06g\x06"\x06\xa0\x03\xc6\x002\xff \xff\x1d\xff\x19\xfd?\xfb\xdb\xfa\xfc\xfa$\xfb}\xf9\xe5\xf7\xf9\xf7\xce\xf8.\xf9b\xf9\xc5\xf9\xc0\xfb\xfa\xfcP\xfc\xba\xfbQ\xfc1\xfe\x9f\xff\x12\x00\xa2\x00\x18\x02Z\x03\x02\x04\xb1\x03\xc5\x03W\x04\x82\x04\x8f\x04U\x04\xb6\x04\x10\x05{\x04\x83\x02\x17\x01\x1d\x00\xa0\xff\xec\xfe\x03\xfe#\xfe\xc2\xfe2\xff\xe6\xfe\x9a\xfe~\x01\x91\x08\xb3\tU\x05\x10\x024\x02\xe4\x05\xa8\x07\xa7\x053\x07I\n\x91\x07v\x02\x95\xfd\xbb\xfd\x96\xff\x01\xfe\x1e\xfb\xbb\xf9S\xf8!\xf8\xf4\xf5\xd6\xf3\xf7\xf3l\xf4d\xf6l\xf7d\xf6b\xf7\xc1\xfa(\xfd\xcf\xfd*\xfdq\xfe\xe9\x01\xa8\x03t\x03\x17\x04B\x07\xce\t\t\t\xeb\x06\x0c\x07\x95\x08\x92\t\xbc\x07O\x06\xfb\x06\xd2\x06U\x04\x00\x02\x92\x00\xdc\x00\x84\x00 \xfeT\xfc\xf1\xfb\x82\xfc\x97\xfb}\xf9\x00\xf8_\xf8\x0b\xf9\xe5\xf8\xe2\xf7\xaa\xf8\xb2\xfa\x10\xfbl\xfa\xf5\xf9Y\xfb\xc0\xfd\xe8\xfe\xec\xfe1\x00\xad\x01\xec\x02E\x03\x13\x03\x9b\x03o\x04\xce\x04\xa8\x04\xb2\x04\x1b\x05\xc0\x05\xd2\x04\xe8\x02z\x01\xbe\x00\xae\x00\x07\x00$\xff|\xff\x8e\x00\x13\x00\x10\xff\x98\xff0\x05{\x0b\x05\t\xaa\x03\x82\x01n\x03
  blah blah~~
  
  that function not return None
  
  ## Environment info
  <!-- You can run the command `datasets-cli env` and copy-and-paste its output below. -->
  - `datasets` version:2.2.1
  - Platform:ubuntu 18.04
  - Python version:3.6.9
  - PyArrow version:6.0.1
  