Calculated from the format_id, width, height.
and format_note fields if missing.
* format_id A short description of the format
- ("mp4_h264_opus" or "19")
+ ("mp4_h264_opus" or "19").
+ Technically optional, but strongly recommended.
* format_note Additional info about the format
("3D" or "DASH video")
* width Width of the video, if known
* height Height of the video, if known
* resolution Textual description of width and height
+ * tbr Average bitrate of audio and video in KBit/s
* abr Average audio bitrate in KBit/s
* acodec Name of the audio codec in use
* vbr Average video bitrate in KBit/s