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• File Decryption in (AESMode.ctr) mode showing Exception Failed to decode data using encoding 'utf-8' in dart ?

  20 novembre 2020, par Jai

  While decoding the video file using aes-ctr mode am getting error like below,

  


  Unhandled Exception: FileSystemException: Failed to decode data using encoding 'utf-8'

  


  Used ffmpeg for encrypting file :

  


  ffmpeg -i samplevideo.mp4 -vcodec copy -acodec copy -encryption_scheme cenc-aes-ctr -encryption_key 76a6c65c5ea762046bd749a2e632ccbb -encryption_kid a7e61c373e219033c21091fa607bf3b8 enc_v1_file.mp4

  


  Used Dart to decode video file :

  


  Future<string> decryptFile(filePath) async {&#xA;    // filePath - Local encrypted file path&#xA;    var encodedKey = &#x27;NzZhNmM2NWM1ZWE3NjIwNDZiZDc0OWEyZTYzMmNjYmI=&#x27;;&#xA;    var encodedIv = &#x27;YTdlNjFjMzczZTIxOTAzM2MyMTA5MWZhNjA3YmYzYjg=&#x27;;&#xA;    var encryptedBase64EncodedString = new File(filePath).readAsStringSync();&#xA;    var decoded = base64.decode(encryptedBase64EncodedString); // Error in this line&#xA;    final key1 = enc.Key.fromBase64(encodedKey);&#xA;    final iv = enc.IV.fromBase64(encodedIv);&#xA;    final encrypter = enc.Encrypter(enc.AES(key1, mode: enc.AESMode.ctr));&#xA;    final decrypted = encrypter.decryptBytes(enc.Encrypted(decoded), iv: iv);&#xA;    final filename = &#x27;${p.basenameWithoutExtension(filePath)}.mp4&#x27;;&#xA;    final directoryName = p.dirname(filePath);&#xA;    final newFilePath = p.join(directoryName, filename);&#xA;    var newFile = new File(newFilePath);&#xA;    await newFile.writeAsBytes(decrypted);&#xA;    return newFilePath;&#xA;}&#xA;</string>

  


• Kivy Crashes when Loading Multiple Audio Files

  26 mars 2022, par Omid Ketabollahi

  I have a music folder and in it I have a script that loads all the files using SoundLoader and assigns them to a variable. I have 9 audio files that I load in the script but it seems like that kivy cannot handle loading many audio files ? When I run my main script I get this error and the program crashes :

  


  Assertion 'pa_atomic_load(&(c)->_ref) >= 1' failed at pulse/context.c:1056, function pa_context_disconnect(). Aborting.


  


  I don't think that this is an issue with the audio files ( I may be wrong ) because I tried loading other files instead of the original ones that I used and I still got this error.

  


  In case you are wondering, this is the code :

  


  import os.path
from typing import Final
from constants import MUSIC_DIRECTORY
from kivy.core.audio import SoundLoader

__all__ = (
    "A_DARK_TIME",
    "BLOOD_PUMPING",
    "BROKEN_VILLAGE",
    "DRUM_COMMERCIAL_B",
    "SUPER_SUSPENSE",
    "THE_HERO_WE_NEED",
    "TROUBLE_IS_BREWING",
    "VIKING_FEAST",
    "WARRIOR_GODS",
)


A_DARK_TIME: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "A-Dark-Time-David-Fesliyan.mp3")
)
BLOOD_PUMPING: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Blood-Pumping-David-Fesliyan.mp3")
)
BROKEN_VILLAGE: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Broken-Village-David_Fesliyan.mp3")
)
DRUM_COMMERCIAL_B: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Drum-Commercial-B-David-Fesliyan.mp3")
)
SUPER_SUSPENSE: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Super-Suspense-David-Fesliyan.mp3")
)
THE_HERO_WE_NEED: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "The-Hero-We-Need-Steve-Oxen.mp3")
)
TROUBLE_IS_BREWING: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Trouble-Is-Brewing-David-Fesliyan.mp3")
)
VIKING_FEAST: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Viking-Feast-David-Fesliyan.mp3")
)
WARRIOR_GODS: Final = SoundLoader.load(
    os.path.join(MUSIC_DIRECTORY, "Warrior-Gods-Steve-Oxen.mp3")
)


  


• How can I display an image from Uint8List with the format AVFormat.RGBA8888 more quickly in Flutter ?

  27 mars, par Salawesh

  I'm looking to display images as quickly as possible. input data is in the form of Uint8List from dart:typed_data, data is encoded in AVFormat.RGBA8888 from ffmpeg.

  


  I'm looking for a solution to improve the performance of my graphics rendering code. And to see if it's possible to do it in a thread (isolate or compute).

  


  Here's my current working code.

  


      final buffer = await ui.ImmutableBuffer.fromUint8List(data.data);
    final descriptor = ui.ImageDescriptor.raw(
      buffer,
      width: data.width,
      height: data.height,
      pixelFormat: ui.PixelFormat.rgba8888,
    );
    final codec = await descriptor.instantiateCodec(); // native codec of ui.Image
    final frameInfo = await codec.getNextFrame();


  


  This is done in my main thread