Audio format Size comparison of PCM/WAV/MP3 (the real size of the MP3 format is only about 12% of the other two formats)

1. When requesting Alibaba Cloud Intelligent Voice Interaction – Speech Synthesis API, its audio encoding format supports PCM/WAV/MP3 format. Default: PCM. It is hoped that the response body should be as small as possible when responding, so it is necessary to confirm the size of the response body in these three formats.

2. Request the interface in Postman, when the response format is MP3, its size is: 187.62 KB. as shown in Figure 1

Figure 1

3. When the response format is PCM, its size is: 1.48 MB. as shown in Figure 2

Figure 2

4. When the response format is WAV, its size is: 1.47 MB. as shown in Figure 3

Figure 3

5. It is found that the size of MP3 accounts for only about 12% of the other two formats. Since this interface is the interface of its own server (this interface transmits the parameters to the Alibaba Cloud API through the transparent parameters), it is suspected that the MP3 transmission happened to be compressed. However, if you look closely at the response header, the response header is exactly the same, especially the values of Transfer-Encoding are all chunked (blocked encoding). Description is not compressed. The real size of the MP3 format is indeed only about 12% of the other two formats.