sample_ What is the relationship between rate, sample and duration

sample_rate( Sampling rate ),sample( sampling ）,duration( Duration ） What's the relationship

It is found that an audio packet is broken into a frame after , Here's the data
nb_samples = 1024
sample_rate = 48000
pkt_duration = 1920
pkt_size = 427
What is the relationship between these values ？

pkt_size = 427 Indicates that the size of the audio compression package is 427 bytes
nb_samples = 1024 It means that after decoding 1024 Sample data
sample_rate = 48000 It means that it needs to be broadcast every second 48K data
pkt_duration = 1920

sample_rate: Sampling rate , Samples per second 48000HZ, Every sample The time is 1/48000 second
nb_samples: Number of samples
Audio playback time , nb_samples The time that the sampling point can play
duration_s=nb_samples*（1/48000） second ,

duration The unit of is not seconds , It's not milliseconds , It is AVStream Number of time bases .
duration=duration_s / av_q2d(st->time_base)
st->time_base yes （1,90k), be av_q2d=1/90k
therefore duration It's actually the number of seconds multiplied by 90K

be :
duration = 1024 * 1/48K *90K = 1920

special case : If you make st->time_base == sample_rate,
be duration=nb_samples.

in addition , pts Is in accordance with the duration To deliver long .