SDK / exoplayer

When playing TrueHD streams, it's possible that the first decoded
buffer is empty, and that the channel count and sample rate are
still unknown. To correct for this, defer determining the format
until a buffer that will actually be output from the decoder has
been obtained, and only then query the channel count and sample
rate.

Issue: #8616
#minor-release
PiperOrigin-RevId: 366246245