I'm setting up an Express.js endpoint that would support decoding a base64 string that came from the client (camera record), which is basically an encoded webm video.The problem is that to validate this, I am trying to create a .webm video file from the encoded base64 string on the server. Unfortunately this results in a video file that cannot be played due to an error of "No video with supported format and MIME type found" (Ubuntu 18.04).I did not have any issue with any other .webm files but also the base64 URL is sure to be correct as I am using it on the cliet as the source of a element to replay what was recorded and works fine.The issue I suspect is something wrong with the code that generates the file on the server route.
import express from "express";import multer from "multer";import fs from "fs";const router = express.Router();// ...router.post("/upload", multer().fields([]), (req, res) => { const formData = req.body; // formData.vid_string is the base64 encoded string fs.writeFileSync( "./test.webm", Buffer.from(formData.vid_string.split(",")[1], "base64") ); res.sendStatus(200);});I have also tried to change fs.writeFileSync code and add "base64" as a third argument but it has the same result.Any input would be appreciated! Thanks!
I have a problem with my own implementation of base64 encoding. I have achieved to get the code below. It only works for text files with the English Letters, I suppose. For instance pdf file is encoded and decoded, it differs single characters.
def base64Encode(data): alphabet = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P","Q","R","S","T","U","V","W","X","Y","Z","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","0","1","2","3","4","5","6","7","8","9","+","/"] bit_str = "" base64_str = "" for char in data: bin_char = bin(char).lstrip("0b") bin_char = bin_char.zfill(8) bit_str += bin_char brackets = [bit_str[x:x+6] for x in range(0,len(bit_str),6)] for bracket in brackets: if(len(bracket) < 6): bracket = bracket + (6-len(bracket))*"0" base64_str += alphabet[int(bracket,2)] # print(brackets[-4:]) #if(bracket[-1:) #print(len(base64_str)) #if(len(base64_str) != 76): # base64_str += "=" return base64_strdef base64Decode(text): alphabet = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","0","1","2","3","4","5","6","7","8","9","+","/"] bit_str = "" text_str = "" for char in text: if char in alphabet: bin_char = bin(alphabet.index(char)).lstrip("0b") bin_char = bin_char.zfill(6) bit_str += bin_char brackets = [bit_str[x:x+8] for x in range(0,len(bit_str),8)] for bracket in brackets: text_str += chr(int(bracket,2)) return text_str.encode("UTF-8")w = open("encode.txt", "w") with open("bla.txt", "rb") as f: byte = f.read(57) while byte: w.write(base64Encode(byte)) w.write("\n") byte = f.read(57) w.close()f.close()w = open("decode.txt", "wb") with open("encode.txt", "r") as f: byte = f.read(77) while byte: w.write(base64Decode(byte)) byte = f.read(77) w.close()f.close()In my opinion, this line "return text_str.encode (" UTF-8 ")" should be without decoding to UTF-8. However, if you leave only "return text_str", gets error: TypeError: 'str' does not support the buffer interface.
bla.txt:
Phil Mercer reports on Cyclone Pam which has ravaged the Pacific nation of Vanuatu. Video courtesy of YouTube/Isso Nihmei at 350.orgSave the Children's Vanuatu country director Tom Skirrow said on Saturday: "The scene here this morning is complete devastation - houses are destroyed, trees are down, roads are blocked and people are wandering the streets looking for help.ĄŚĆŹŻÓencode.txt
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.txt
Phil Mercer reports on Cyclone Pam which has ravaged the Pacific nation of Vanuatu. Video courtesy of YouTube/Isso Nihmei at 350.orgSave the Children's Vanuatu country director Tom Skirrow said on Saturday: "The scene here this morning is complete devastation - houses are destroyed, trees are down, roads are blocked and people are wandering the streets looking for help.ÄÅÄŹŻÃThe same text encoded by page: http://www.motobit.com/util/base64-decoder-encoder.asp
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It is the same, except "=", which omitted to implement due to the error at the very beginning of the file.
And sample originale file in pdf:
%PDF-1.5%µµµµ1 0 obj<</Type/Catalog/Pages 2 0 R/Lang(pl-PL) /StructTreeRoot 8 0 R/MarkInfo<</Marked true>>>>endobj2 0 obj<</Type/Pages/Count 1/Kids[ 3 0 R] >>endobj3 0 obj<</Type/Page/Parent 2 0 R/Resources<</Font<</F1 5 0 R>>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.32 841.92] /Contents 4 0 R/Group<</Type/Group/S/Transparency/CS/DeviceRGB>>/Tabs/S/StructParents 0>>endobj4 0 obj<</Filter/FlateDecode/Length 110>>streamxœUÌ€@ྰï0QËÝ®Èiž?(†kb°hòý«ZD˜4ßÀΨ*;…¡xº ¨#“íªFrÄI!w…˜2ËQ81®D<™ÇS=Ó’léŠ82µ·>^åŒÊO- >[´SÀ endstreamendobj5 0 obj<</Type/Font/Subtype/TrueType/Name/F1/BaseFont/ABCDEE+Calibri/Encoding/WinAnsiEncoding/FontDescriptor 6 0 R/FirstChar 32/LastChar 97/Widths 15 0 R>>endobj6 0 obj<</Type/FontDescriptor/FontName/ABCDEE+Calibri/Flags 32/ItalicAngle 0/Ascent 750/Descent -250/CapHeight 750/AvgWidth 521/MaxWidth 1743/FontWeight 400/XHeight 250/StemV 52/FontBBox[ -503 -250 1240 750] /FontFile2 16 0 R>>endobj7 0 objAnd after executing script:
%PDF-1.5%µµµµ1 0 obj<</Type/Catalog/Pages 2 0 R/Lang(pl-PL) /StructTreeRoot 8 0 R/MarkInfo<</Marked true>>>>endobj2 0 obj<</Type/Pages/Count 1/Kids[ 3 0 R] >>endobj3 0 obj<</Type/Page/Parent 2 0 R/Resources<</Font<</F1 5 0 R>>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 595.32 841.92] /Contents 4 0 R/Group<</Type/Group/S/Transparency/CS/DeviceRGB>>/Tabs/S/StructParents 0>>endobj4 0 obj<</Filter/FlateDecode/Length 110>>streamxUÌ@ྰï0QËÝ®Èi?(kb°hòý«ZD4ßÀΨ*;¡xº ¨#íªFrÄI!w2ËQ81®D<ÇS=Ólé82µ·>^åÊO- >[´SÀ endstreamendobj5 0 obj<</Type/Font/Subtype/TrueType/Name/F1/BaseFont/ABCDEE+Calibri/Encoding/WinAnsiEncoding/FontDescriptor 6 0 R/FirstChar 32/LastChar 97/Widths 15 0 R>>endobj6 0 obj<</Type/FontDescriptor/FontName/ABCDEE+Calibri/Flags 32/ItalicAngle 0/Ascent 750/Descent -250/CapHeight 750/AvgWidth 521/MaxWidth 1743/FontWeight 400/XHeight 250/StemV 52/FontBBox[ -503 -250 1240 750] /FontFile2 16 0 R>>endobj7 0 objThe differences are for instance at the beginning of line 15 and 16.
My goal is to load the file and encode it in base64 and then decode and obtain the same file. Fit for use.I suppose that the error is in the data read or write or encoding. Any suggestions?
I need an advice on decoding base64. I will be doing it in c#.
The thing is, I don't know what type of format the decoding will output it may be text, XML, images or PDF. I only have the base64 encoded string.
How do you guys advice me to proceed? Any suggestions?
I didn't find a response in the search section, so I came here.
I've made some functions that convert images to Base64 strings, nothing far from normal:
func imagePickerController(_ picker : UIImagePickerController, didFinishPickingMediaWithInfo info : [UIImagePickerController.InfoKey : Any]) { if let pickedImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage { let pickedImageBase64: String = ( pickedImage .pngData()? .base64EncodedString() )!; NSLog("image base64: %@", pickedImageBase64); self.imageHandler(pickedImageBase64); }}Nothing weird, I pick an image from the camera get the PNG data, ask for it as base64-encoded string, I put a log of that string, and toss it over to the an image handler.
Inside the application, I can convert that base64-encoded string to images with no problem, at all.
However, when I upload that base64-encoded string to a server, or even when I copy what's in the NSLog entry, I can't decode it using base64 command in Shell, or using any service in the web.
Tried with our good-old-friend: cat file.txt | base64 --decode > myimage.png; but "it's damaged".
However, when I copy that string, hard-code it into another iOS App, and try to decode it, works just fine.
I hope someone can helps. Thanks in advance.
Since two weeks, I'm trying and reading to solve this problem, but everything I tried didn't worked :-(
I'm using python 2.7.
I do have, as far as I understand, a base64-string from the format: AAMkADk0ZjU4ODc1LTY1MzAtNDdhZS04NGU5LTAwYjE2Mzg5NDA1ZABGAAAAAAAZS9Y2rt6uTJgnyUZSiNf0BwC6iam6EuExS4FgbbOF87exAAAAdGVuAAC6iam6EuExS4FgbbOF87exAAAxj5dhAAA=
I want to convert it to a hex-string. Which should result in 00000000194BD636AEDEAE4C9827C9465288D7F40700BA89A9BA12E1314B81606DB385F3B7B100000074656E0000BA89A9BA12E1314B81606DB385F3B7B10000318F97610000
I tried it with the following code:
def itemid_to_entryid(itemid): decoded_val = base64.b64decode(itemid) decoded_val = ''.join( ["%02X" % ord(x) for x in decoded_val ] ).strip() decoded_val = decoded_val.upper() return decoded_valitemid = 'AAMkADk0ZjU4ODc1LTY1MzAtNDdhZS04NGU5LTAwYjE2Mzg5NDA1ZABGAAAAAAAZS9Y2rt6uTJgnyUZSiNf0BwC6iam6EuExS4FgbbOF87exAAAAdGVuAAC6iam6EuExS4FgbbOF87exAAAxj5dhAAA='entryid = itemid_to_entryid(itemid)print(entryid)which always returns me the following: 0003240039346635383837352D363533302D343761652D383465392D30306231363338393430356400460000000000194BD636AEDEAE4C9827C9465288D7F40700BA89A9BA12E1314B81606DB385F3B7B100000074656E0000BA89A9BA12E1314B81606DB385F3B7B10000318F97610000
and I really don't get, what I'm doing wrong and really would appreciate any help in understanding what I'm doing wrong.
Kind regardsBen
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