Obtaining PSSH

README.md

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+# Obtaining PSSH
+
+
+
+## Getting started
+
+4 methods to find PSSH:
+
+1) The simplest one: PSSH is clearly indicated in MPD file. Download MPD file (browser add-on "MPD Detector" will give you MPD link or filtering for `mpd` in the `network` tab of devoloper tools (ctrl + shift + c)), open it with Notepad, search for pssh value.
+
+2) If there is KID, but no PSSH in MPD, calculate PSSH by using KID:
+
+Using [this](https://tools.axinom.com/generators/PsshBox "this") website you can get the PSSH by entering in the `urn:uuid:` into the `System ID` field and entering the `cenc:default_KID=` into the `KEY IDs` field without the quotes `""`
+
+Eample:
+![One:](example_one.png?raw=true "One")
+
+## Recommended method
+
+3) [EME Logger Script](https://greasyfork.org/en/scripts/373903-eme-logger "EME Logger Script") (installed on [Tampermonkey](https://www.tampermonkey.net/ "Tampermonkey") add-on) will give you init data. That's your PSSH. This can be found on Developer Tools (ctrl + shift + c) > Console, in the filter bar search for `MediaKeySession::generateRequest` you will find Init Data.
+
+**Optional, may be rquired:**
+
+If that Init Data is very very long, convert it to HEX:
+https://base64.guru/converter/decode/hex
+
+Here's what mine looked like before conversion.
+![Two:](example_two.png?raw=true "Two")
+
+
+After Base64 > HEX conversion, you will find a Widevine-PSSH box, this can be found easily by searching with ctrl + f and searching for `70737368` 
+
+PSSH header is always in a `000000xx70737368` where the `xx` is varied and can be from 1-9 in both x spots.
+ You always want to copy the 6 `0`'s before the xx as well.
+
+Example:
+![Three:](example_three.png?raw=true "Three")
+
+The end of the header is always then followed by 8 more `0`s, if you see this, you are in the right place.
+
+Once you find the header start at the beginning 0 from the header and copy until the end of the converted hex, it should look like this
+
+Example:
+![Four:](example_four.png?raw=true "Four")
+
+In this case the full value was `000000577073736800000000edef8ba979d64acea3c827dcd51d21ed0000003708011210162f7d326cf24f6dbd1319bc572bbc151a0b62757964726d6b65796f732210162f7d326cf24f6dbd1319bc572bbc152a024844`
+
+convert the hex back into base64 using
+https://base64.guru/converter/encode/hex
+
+Example:
+![Five:](example_five.png?raw=true "Five")
+
+In this case we got the PSSH value of `AAAAV3Bzc2gAAAAA7e+LqXnWSs6jyCfc1R0h7QAAADcIARIQFi99MmzyT229Exm8Vyu8FRoLYnV5ZHJta2V5b3MiEBYvfTJs8k9tvRMZvFcrvBUqAkhE`
+
+Congrats, you have the PSSH!
+
+4) Using init files
+
+You can use [this tool](https://cdm-project.com/CDM-Tools/Obtaining-PSSH/src/branch/main/get_pssh_from_init.py "this tool") to obtain the PSSH from an init file

get_pssh_from_init.py

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+import base64
+
+import requests
+import xmltodict
+
+
+def read_pssh_from_bytes(bytes: bytes):
+    pssh_offset = bytes.rfind(b"pssh")
+    _start = pssh_offset - 4
+    _end = pssh_offset - 4 + bytes[pssh_offset - 1]
+    pssh = bytes[_start:_end]
+    return pssh
+
+
+url = input("Enter Init segment url: ")
+headers = {
+    # "Range": "bytes=0-962",
+}
+print("Downloading...")
+
+res = requests.get(url, headers=headers)
+if not res.ok:
+    print(f"Could not download init segment: {res.text}")
+
+pssh = read_pssh_from_bytes(res.content)
+if pssh is not None:
+    print(f"PSSH: {base64.b64encode(pssh).decode('utf8')}")
+else:
+    print("Failed to extract PSSH!")