encoder | 易学教程

Spark dataset encoders: kryo() vs bean()

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问题 While working with datasets in Spark, we need to specify Encoders for serializing and de-serializing objects. We have option of using Encoders.bean(Class<T>) or Encoders.kryo(Class<T>) . How are these different and what are the performance implications of using one vs another? 回答1: It is always advisable to use Kryo Serialization to Java Serialization for many reasons. Some of them are below. Kryo Serialization is faster than Java Serialization. Kryo Serialization uses less memory footprint

Which video encoders are guaranteed to be supported by android MediaCodec API?

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问题 Testing video encoding with the MediaCodec API in several devices, I noticed all of them have encoders for h264, h263, and MPEG-4. Are any of these guaranteed to be supported by all devices which have at least Jelly Bean, even if the actual encoding done by MediaCodec is done by software instead of hardware? 回答1: The Android Compatibility Definition Document (CDD) defines a set of mandatory features. Google "Android <version> CDD" to find the appropriate one. For example, if you open the 4.3

Strange bmp black output from BitmapSource - any ideas?

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问题 I have a byte[] array with the bgra bytes of an image, from which I produce a BitmapSource like so: BitmapSource bmsOut = BitmapSource.Create( iPixelWidth, iPixelHeight, 96, 96, PixelFormats.Bgra32, null, bytOutput, iStride); this displays fine on an wpf Image element. HOWEVER, when I then try to create a file from the BitmapSource: private void mtdSave(BitmapSource bitmapSource, string path, BitmapEncoder encoder) { using (var stream = new FileStream(path, FileMode.Create)) { encoder.Frames

Python sklearn - Determine the encoding order of LabelEncoder

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问题 I wish to determine the labels of sklearn LabelEncoder (namely 0,1,2,3,...) to fit a specific order of the possible values of categorical variable (say ['b', 'a', 'c', 'd' ]). LabelEncoder chooses to fit the labels lexicographically I guess as can be seen in this example: from sklearn.preprocessing import LabelEncoder le = LabelEncoder() le.fit(['b', 'a', 'c', 'd' ]) le.classes_ array(['a', 'b', 'c', 'd'], dtype='<U1') le.transform(['a', 'b']) array([0, 1]) How can I force the encoder to

encoding mp3 from a audio stream of PyTTS

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问题 I work on text-to-speech trasforming text, in audio mp3 files, using python 2.5. I use pyTSS as a python Text-To-Speech module, to transform text in audio .wav files (in pyTTS is not possible to encode in mp3 format directly). So after that, I code these wav files, in mp3 format, using lame command line encoder. Now, the problem is that, I would like to insert (in particular point of an audio mp3 file, between two words) a particular external sound file (like a sound warning) or (if possible

Problems of using MediaCodec.getOutputFormat() for an encoder in Android 4.1/4.2 devices

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问题 I'm trying to use MediaCodec to encode frames (either by camera or decoder) into a video. When processing the encoder output by dequeueOutputBuffer(), I expect to receive the return index = MediaCodec.INFO_OUTPUT_FORMAT_CHANGED, so I can call getOutputFormat() to get the encoder output format as the input of the currently used ffmpeg muxer. I have tested some pad/phone devices with Android version 4.1~4.3. All of them have at least one hardware video AVC encoder and is used in the test. On

short way to write VHDL priority encoder

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问题 Could you tell me if there is a better way to write a priority encoder in VHDL than just using if-else statements? I mean, I have got this code and it works, but could it be written shorter? Switch is an std_logic_vector. Thanks for your help! shifting : PROCESS(CLK_IN, new_length_ready, switch) VARIABLE highest_switch : INTEGER RANGE 0 TO 15 := 15; BEGIN -- priority encoder, changes the length of the snake track -- ( i.e., number of leds for the snake to move ) IF switch(15) = '1' THEN

Developing for Linux

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问题 I want to develop multimedia encoder for Linux. I want to make use of ready command line codecs like ffmpeg. I want to build nice GUI for that & pass arguments to command line encoders. I am thinking to use Qt. (Is it possible?) I don't know anything about Linux programming, but I have been an Ubuntu user for 8 months. Please provide me with links to tutorials. (I've tried the Ubuntu forums but it's all beginners stuff in there!) I am in need of tips from you guys. I am ready to learn

Morse Code Converter in C

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问题 Yes its homework We were suppose to have char 2D array holding character with size limit of 255 char char string[100][255]; Program neede: change the input morse code by a user to alphabet/English letter (Capital Letters) Sample Input 2 .... . .-.. .-.. --- / .-- --- .-. .-.. -.. .--- --- -.- . Sample OutPut Case#1: HELLO WORLD Case#2: JOKE My only idea is to have the first characters of a word that is inputed by the user.. to be.. checked if its '.' or '-' then scrupulously and manually

Will all phones support YUV 420 (Semi) Planar color format in h.264 encoder?

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Preambule: This may sound like a very specific question, but this is actually a go / no go to build an API 16+ Android application using MediaCodec that is compatible with most phone. I have an application with a h.264 MediaCodec that receives data from a buffer - and not a surface since I'm doing a lot of manipulations on the image. When creating the Encoder , I iterate through the list of possible encoders from the phone to make sure I'm using a proprietary encoder if any. This part is not a problem. The problem is that each encoder has its color format preference. This may lead to color