About definition for terms of audio codec -

-

When I was reading the coca audio queue document, I found several words in the audio codec Is defined in the structure.

Here are the conditions: 1. 1. Sample rate 2. Packet 3. 3. Frame 4. Channels

I have sample rate and < Know about the code> channel . Why was I confused by two others? What do the other two words mean?

In addition to this, you can answer this question by example. For example, I have a dual-channel PCM-16 source with a sample rate of 44.1kHz, which means that 2 * 44100 = 88200 bytes are PCM data per second. But about packet and frames

Thank you in advance!

You are already familiar with the sample rate definition. The sampling frequency or sampling rate, FS, is defined as the number of samples obtained in a second (samples per second), thus for the sampling rate of FS = 1 / T and 44100 Hz, you have 44100 samples per sample. Seconds (per audio channel).

The number of frames per second in the video is the same concept as the number of samples per second in the audio. Frame for our eyes, our ear samples extra Infos

If you have a 16-bit depth stereo PCM, then that means you have 16 * 44100 * 2 = 1411200 bits per second = & gt; ~ 172 kb per second = & gt; Approximately 10MB per minute.

For definitions from Apple: 

  Sample: A number representing the value of an audio channel at one point at the same time. Frame: Group of one or more samples, with a sample for each channel, represents the audio on all channels at the same point on time. Packet: A group of one or more frames represents the smallest encoding unit of audio format, and audio for all channels in a small amount.   
 As you can see, there is a subtle difference between audio and video frame ideas. You have stereo audio 44.1 KHz: 88200 samples and 44100 frames in a second.  
 Many frames in the compressed format packet such as MP3 and AAC packs (these packets can be written in MP3 files for example, they can be interfaced efficiently with video content). You understand that dealing with large packets helps to identify bit patterns for better coding efficiency.  
 
 MP3, for example, uses 1152 frames of packets, which is the basic nuclear unit of MP3 stream. PCM audio is just a series of samples, so it can be split into different frames, and there really is no packet size in it.   
 You can do 1024 (or 960) for AAC frames per packet. It has been described in Apple Document:  
 
 Pack of audio data In the number of frames for uncompressed audio, the value is 1. For variable bit-rate formats, the value is a fixed number, such as 1024 for AAC. For variables, a variable number of packet frames, such as Ogg Vorbis, set this field to 0.   
 In a MPEG-based file format, a packet is referred to as  data  frame (not being in conjunction with the previous audio frame hold). For more information on the subject, see Brad's comment.

Comments

Post a Comment

Popular posts from this blog

python - Writing Greek in matplotlib labels, titles -

-
Image
I'm trying to write some text for labels, shape titles etc. with my plots, but no benefit till now Has not happened . I do not want to print specific characters (I know how to use special characters), I want to write the entire text in Greek (maybe Unicode and text ' ?). , suggesting that I would like to mention that for some reason I can not get matplotlib to cooperate with Tex (using IPython notebook from Anaconda in Ubuntu 14.10) so that there really is an option Will not be the first. I tried loading the Arial font and it loads successfully but again I get square blocks instead of characters. I import matplotlib.font_manager FM PROP = FM Font Properties (fname = '/ usr / share / fonts / truetype / msttcorefonts / Arial.ttf') And then to display the string I u'Î? ? I ?? Î¿Ï ?? ÎμÎ »second ?? μΠ± i ?? I ± i ?? I ?? Used ο किया? ? Î¿Î¼Î¿Î¯Ï ?? I ?? I · I ?? ' . Ariel is considered to be fully presented to Greek and I have used it many times ...
Read more

c# - LINQ to Entities does not recognize the method 'Int32 IndexOf(System.String, System.StringComparison)' method -

-
I have performed a linq query using Entityframework as below GroupMaster getGroup = Null; GetGroup = DataContext.Groups.FirstOrDefault (item = & gt; keyword.IndexOf (item.Keywords, StringComparison.OrdinalIgnoreCase)> = 0 & amp; amp; item.ISNAmd) I found an exception like the method when executing it LINQ units do not recognize the 'Inter 32 index of (system string, system. String compromise)' method, and This method can not be translated to Store expression. Includes () method is sensitive by default, then I need to convert to minimize. Is there any method in which a string match match is examined and whether there is any method to solve the index question of the method? You actually have four options Databases globally Change the colon of it can be done in many ways, a simple Google search should reveal to them. Change the mix of individual tables or columns. Use a stored procedure and specify the call statement on your query Perform...
Read more

Pygame memory leak with transform.flip -

-
Today I came across an interesting issue which, by writing a small side scroller, instead of a sprite sheet, I was planning to use because I lacked a good "packer" for making phantom sheets (and honestly with patience and passion as it is only a test project). Anyway, I showed the animation running on the right of 8 PNG (with transparency). I considered it a good idea to prepare the flipped images to run on the left in the consultant, and the frame is not framed when the game is running (Flip actually consumes a lot of CPU like I Was measured). > To get access to the loop, I get the memory leak self.move_l = [# 8 PNG images with transparency to the right] For the self in IMG. Move_l: self.move_r.append (pygame.transform.flip (img, true, false) error traceback: traceback (most recent Call final): The file "D: \ Python 34 \ _Projects \ efg \ efg.py", in line 196, in the & lt; module & gt; main = master program ((1024, 680)) "D: \ Python ...
Read more