read from a provided <a href="../ExtractorInput.html" title="interface in com.google.android.exoplayer2.extractor"><code>ExtractorInput</code></a>. Must not be called before <a href="../Extractor.html#init(com.google.android.exoplayer2.extractor.ExtractorOutput)"><code>Extractor.init(ExtractorOutput)</code></a>.

 <p>A single call to this method will block until some progress has been made, but will not
 block for longer than this. Hence each call will consume only a small amount of input data.

 <p>In the 