A method for adjusting a storage bitrate of a data buffer with a buffer size includes: storing data at a selected storage bitrate into the data buffer; writing the stored data from the data buffer into a storage device attached to the data buffer with a predetermined writing speed; monitoring a data amount of the stored data in the data buffer; monitoring a trend of change in the data amount; determining whether the data amount has reached a first ascending threshold, the first ascending threshold being below the buffer size of the data buffer; and in response to the data amount reaching the first ascending threshold and the trend of change in the data amount being an ascending change, reducing the storage bitrate in the data buffer.