I was recently asked a similar question by a colleague who was starting to program in C. And I thought this was a good opportunity to share my understanding of this issue. Because even experienced programmers do not always have similar points of view on this matter.
Partly this is a matter of taste, so if anyone is interested in how I do it, welcome to the cat.
Despite the fact that “the whole truth” about h-files is contained in the corresponding section of the description of the gcc preprocessor, I will allow myself some explanations and illustrations.
So, literally, a header file (h-file) is a file containing C declarations and macro definitions intended for use in several source files (c-files). Let's illustrate this.
It is easy to notice that functions 1 and 2, as well as macro 2, are mentioned in both files. And since including the header files produces the same results as copying the contents into each C file, we can do the following: 
Thus, we simply extracted the common part of the two files and placed it in the header file.
But is the header file an interface in this case?
- If we need to use the functionality that functions 1 and 2 implement somewhere else, then Yes
- If macro 2 is intended only for use in the Unit1.c and Unit2.c files, then it has no place in the interface file
The answer to this question depends on the implementation details of the interface functions and where they are implemented. For example, if you make the diagrams more detailed, you can imagine a scenario where interface functions are implemented in different files:
This implementation option leads to high code coherence, low testability and complexity. reuse such modules.
In order to avoid such difficulties, I always consider the C file and the header file as one module. In which,
- The header file contains only those declarations of functions, types, macros that are part of the interface of this module.
- The C file, in turn, must contain the implementation of all functions declared in the h-file, as well as private types, macros and functions that are needed to implement the interface.
The diagram shows that in fact we are dealing with two independent modules, each of which has its own interface in the form of a header file. This makes it possible to use only the interface that is really needed in this particular case. Moreover, these modules can be tested independently of each other.
The reader probably noticed that macro 2 from the header file was again returned as a copy in both C files. Of course, this is not very convenient to maintain. But making this macro part of the interface is not correct.
In such cases, I prefer to make a separate header file containing the types and macros needed by several C files.
I hope I was able to identify those entities that need to be placed in header files. And also, show the difference between interfaces and files containing declarations and macros required by several C files.
Thank you for your attention to the material.
Now we will talk about how to open H264. This is a special type of video file compression. This decision often used to record videos in AVCHD format by recorders, surveillance systems and video cameras.
Definition
First of all, it is worth touching on in more detail the question of what the H264 extension is. We'll describe how to open it a little later. The specified video compression format was adopted for standardization. The solution is intended primarily to achieve high level stream compression while maintaining decent quality. Another name for H264 is AVC.
With the same in the new standard, it will take up much less space on the hard drive in comparison with MPEG-4 (by about 50%). At the same time, AVC codecs are more demanding in terms of system resources than ASP-based solutions (for example, DivX and XviD). Most modern TVs, as well as hardware players, reproduce specified files. A personal computer can cope with this task. Many player programs support playback of H264 format videos. However, some applications may require the installation of additional codecs.
If you have an H264 file in front of you, the programs that we will consider separately below will tell you how to open it.
VLC
Now we will talk about a multifunctional player that has a full set of capabilities that allow you to watch videos with maximum comfort. There is an H264 codec here. Thus, the program knows how to open the format we are interested in. The solution is distributed free of charge and is constantly being developed.
VLC player has many advantages. It is worth noting that it works on Mac, Windows and Linux. The user gets the opportunity to install various modules and amazing playback quality, which is customizable individually. Video filters present in the player allow you to control the settings.
The built-in testing module allows you to maintain the optimal recording quality. If we talk about the player interface, in this matter the developers listened to the opinions of users. Even the default player option is not satisfactory. Anyone can install an additional skin to their liking.
The player has a convenient playlist that allows you to set the order of played files, as well as view brief information about them. As for the special tag editor, it provides the ability to compose your own video collection.
A notable feature of VLC is the ability to play damaged or incompletely downloaded files. Another feature of the program is on the computer. VLC is incredibly easy to use and will help solve the issue at hand, but it is not the only one.
Media Player Classic
Next, we will discuss a fast, functional, convenient and small player that will help you play files of the format you are interested in. So, if you have an H264 format in front of you, the classic one will tell you how to open it. Media Player. The solution is distributed freely. It's written on Has an open source code, works only on Windows OS.
The built-in WMP will tell you how to open H264
Sometimes the solution is closer than it seems, because the player built in by default can help us. Windows system, developed by Microsoft. In this case, files are decoded using DirectShow filters. The program has a clear interface and an unobtrusive, no-frills design. There is a special library where playable files are stored.
BSplayer
We will talk about a high-quality multifunctional player that will also help you open video files compressed in the H264 format. The application supports many skins. BSplayer is free program, which is designed for international use. There are advanced options for searching, editing and displaying subtitles.
It is worth noting that the functionality of the application does not make it demanding on computer resources. BSplayer is suitable for installation even on weak PCs. The program supports special control using remote controls. Thanks to the built-in Progressive Rendering function, you can reliably protect the stream from random frame drops. Capture, slow and fast playback, and bookmarking are also available. This player is easy to operate and configure. The program is available in Russian. All multimedia materials stored on personal computer, are displayed in a special library.
Other options
To solve the question of how to open H264, a number of other applications are suitable, including QuickTime Player, Roxio Creator, CyberLink PowerDVD, Corel VideoStudio, Elecard, Xilisoft Video. Let's talk about the latter in more detail.
We will talk about a universal assistant for video files. It is also a powerful converter. The program is paid. It has a simple interface. The controls will be clear to the average PC user. The application will allow you to extract audio tracks from a video stream, saving them in your preferred format. Experienced users can add a variety of effects; they will make the video more “live” (and, if desired, on the contrary, black and white). Work with subtitles is available. The function of extracting the required number of images from a recording is also useful. If necessary, the video file can be divided into several small parts. It’s convenient that the processes go very quickly.
Now you know how to open H264. There are many programs for this, you just have to choose the most suitable one.
Developers multimedia players They try to make their products universal so that they reproduce as many formats as possible. Unfortunately, even the best and most famous multimedia players cannot cover the entire range of video formats, which are often qualitatively different from each other even when using the same extension. The biggest problems arise with special or proprietary formats that require special software or at least special codecs to play.
What is the H264 format and where is it used?
An example of such “difficult” formats is H264, developed by specialists from the ITU Video Coding Experts Group and used to save video to a file from outdoor surveillance cameras and car DVRs. In addition to recording a video stream, the H264 format is used to transmit video in mobile networks. The use of h264 in surveillance cameras is determined, first of all, by excellent data compression, which makes even long videos compact and of sufficient quality.
Thus, video compressed using the H.264 codec will take up almost half as much disk space as MPEG-4 of the same quality. This allows you to save Internet traffic and space on physical media, but the format also has its drawbacks, in particular, it is more demanding on the resources of the recording device than DivX or XviD. Another drawback is its proprietary nature. Even though the files have the same H264 extension, their encoding algorithm may differ depending on what device they were recorded with.
Programs for viewing files in H264 format
A reasonable question arises - how to open the h264 file and what programs are needed for this. The corresponding software is usually supplied with recording devices, but if you found the video on the Internet, you can try to open the h264 format using third-party players. Try it, because you can’t give a 100% guarantee that the video will open.
H264 video file player from the developer Shenzhen VStarcam Technology. The player is equipped with the simplest file manager, h264 to AVI converter, supports video rewinding, audio playback, fast viewing, still frame capture and printing. Among the shortcomings of the current version, it should be noted that images with different proportions than standard ones are displayed incorrectly; the image can be stretched vertically.
One of the most popular and powerful media players that can play most well-known multimedia formats, which include H264/AVC. It can open an h264 file from surveillance cameras, but not all models, but the player opens H264/AVC encoded video with the MP4 extension without any problems. VLC Player has a built-in converter that can help you convert videos to a more common format. If you cannot immediately open h264 in VLC, it is recommended to install the ffdshow tryouts, AC3Filter and Haali Media Splitter decoders.
Datakam Player
How else can you view the h264 file from the DVR? Search the Internet for a special application called Datakam Player, also known as Registrator Viewer. It is an alternative to players supplied with car recorders; it supports playback of video recorded using DATAKAM, DOD, ProCam, CamBox, Papago, Digma, xDevice, AdvoCam and many other devices. The player's capabilities include working with maps, video scaling and frame-by-frame viewing, searching and grouping files.
Desktop programs for converting H264 to AVI
If an H264 video needs to be posted on the Internet for free access, it is advisable to convert it to AVI or MP4 so as not to create viewing difficulties for users who have downloaded it. To do this, you can use the following converter programs.
A free converter designed to convert different formats between each other. The program is designed for converting videos into supported formats mobile devices, but can also be used for H264 conversion. Relatively simple, convenient, allows you to configure bitrate, FPS and other video parameters, supports distributed encoding using servers local network. To work, it requires installation of ffdshow tryouts, Haali Media Splitter, AVisynth program and the Net Framework component.
Powerful video converter with built-in codecs and wide support for multimedia formats, including H264. It has flexible settings, allows you to change the parameters of the converted video, add menus, subtitles and other elements. The program is simple to use - drag an H264 video into the “Source file” field, select your preferred format on the “Formats” tab and click the “Start” button.
Online H264 to AVI converters
You can also convert video recorded by a surveillance camera or DVR using online services. The method is convenient because it does not require installation on a computer. third party programs and additional codecs.
Online-Convert.com
A popular online file converter in RuNet. It cannot be said that it was designed to work only with video, but it supports the H264 format and this is the main thing. Conversion can be done with default settings or with edit elements. The service allows you to change the video size, its bitrate, and supports deletion audio track, cropping, rotation vertically and horizontally. It is also possible to select a codec. The output format can be selected from AVI, MKV, MOV, MP4, 3GP, 3G2, FLV and MPEG.
A service similar in functionality, which can also be used as an H264 to AVI converter online. Supports changing video size, bitrate and FPS, cropping and reverse. Besides AVI, downloaded videos can be converted to GIF, WMV, OGG, MOV, MKV, MP4 and WEBM.
Filezigzag.com
And finally, another good online converter with support for the H264 format. Can convert to AVI, 3G2, 3GP, FLV, MKV, MOV, MP4, MPG, WEBM and WMV. The service differs from the two previous ones in less functionality and a slightly different sequence of actions. The conversion is performed in Filezigzag.com with default settings (they cannot be changed), to get the result you need to specify Mailbox, albeit not working. The processed file is saved to local computer or to cloud storage.
If you have installed on your computer antivirus program Can scan all files on your computer, as well as each file individually. You can scan any file by clicking right click mouse on the file and selecting the appropriate option to scan the file for viruses.
For example, in this figure it is highlighted file my-file.h, then you need to right-click on this file and select the option in the file menu "scan with AVG". When you select this option, it will open AVG Antivirus, which will perform the check this file for the presence of viruses.
Sometimes an error may occur as a result incorrect installation software , which may be due to a problem encountered during the installation process. This may interfere with your operating system link your H file to the correct application software , influencing the so-called "file extension associations".
Sometimes simple reinstalling MacroMates TextMate may solve your problem by linking H correctly with MacroMates TextMate. In other cases, problems with file associations may result from bad software programming developer and you may need to contact the developer for further assistance.
Advice: Try updating MacroMates TextMate to latest version to make sure you have the latest patches and updates installed.
This may seem too obvious, but often the H file itself may be causing the problem. If you received the file via an attachment Email or downloaded it from a website and the download process was interrupted (for example, a power outage or other reason), the file may become damaged. If possible, try getting a new copy of the H file and try opening it again.
Carefully: A damaged file may cause collateral damage to a previous or existing malware on your PC, so it is very important to keep an updated antivirus running on your computer at all times.
If your file is H related to the hardware on your computer to open the file you may need update device drivers associated with this equipment.
This problem usually associated with media file types, which depend on successfully opening the hardware inside the computer, e.g. sound card or video cards. For example, if you are trying to open an audio file but cannot open it, you may need to update sound card drivers.
Advice: If when you try to open file H you get .SYS file error message, the problem could probably be associated with corrupted or outdated device drivers that need to be updated. This process can be made easier by using driver update software such as DriverDoc.
If the steps do not solve the problem and you are still having problems opening H files, this may be due to lack of available system resources. Some versions of H files may require a significant amount of resources (e.g. memory/RAM, processing power) to properly open on your computer. This problem occurs quite often if you are using a fairly old computer. Hardware and at the same time a much newer operating system.
This problem can occur when the computer has difficulty completing a task because operating system(and other services running in background) can consume too many resources to open the H file. Try closing all applications on your PC before opening C/C++/Objective-C Header File. Freeing up all available resources on your computer will provide the best conditions for attempting to open the H.
If you completed all the steps described above and your H file still won't open, you may need to run equipment update. In most cases, even when using older versions of hardware, the processing power may still be more than sufficient for most custom applications(unless you're doing a lot of CPU intensive work like 3D rendering, financial/scientific modeling or multimedia intensive work). Thus, it is likely that your computer does not have enough memory(more commonly called "RAM", or RAM) to perform the file open task.
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