CN104159168A - Computing method suitable for audio and video time format conversion - Google Patents

Abstract

The present invention discloses a computing method suitable for audio and video time format conversion, which is achieved by the means of loading a media file, reading actual playing time, cutting each video unit time into 1 billion parts, rounding off to obtain an identical frame number, obtaining time with 10-digit accuracy, and converting into standard SMPTE format time. Compared with prior art, the present invention has advantages as follows: common formats are supported; files with various frame rates, such as 23.97, 29.97, 60, 120 are supported; all the audio and video files that can be played in a computer are supported; all playable audio and video files which can output time codes with a same specification at the same time can be synchronized; the computing method is universal on all playing platforms and is accurate to 1/1000000000 second, so that the method greatly improves the accuracy, is convenient in use and has popularization and application value.

Description

A Calculation Method Applicable to Audio-Video Time Format Conversion

technical field

The invention relates to a multimedia time format calculation method, in particular to a calculation method suitable for audio and video time format conversion.

Background technique

At present, the standard SMPTE time code can only be used in professional audio and video fields, but not in civilian fields. Typical references are controlling peripherals for video capture and editing. This process requires identifying each frame of audio and video. The method they use is to use SMPTE timecode for precise synchronization. The current editing system usually controls three or more peripheral devices like tape drives, etc., and can switch between them. The computer must execute the command precisely, so the audio and video location address must be obtained at a specific time. There are many ways for a processing program to use timecode, such as: 1. Updating audio and video during the entire editing process 2. Synchronizing audio and video 3. Synchronizing multiple peripherals, etc. If this part cannot be handled accurately, the most typical negative case is our common movie audio and video out of sync.

The film industry SMPTE standard that we usually use is 24 frames per second. However, the films we usually shoot with ordinary equipment (such as mobile phones, emergency DV, SLR, card players, etc.) do not have a unified LTC writing function, and the frame rates are not the same, but not limited to 23.97 frames 29.97 fps, 60 fps, 120 fps and more. Therefore, such audio-visual products are not accepted by the professional market. As a result, it has always been outside the professional threshold to shoot movies with mobile phones for editing. It cannot be used in the professional control market such as special effects occasions that require precise synchronous control of multi-channel and multi-equipment.

Moreover, movies with different frame rates cannot be synchronized simply by calculation. If they are divided by milliseconds, the resulting numbers will also be different. It is also flawed to do synchronization completely according to SMPTE. For example, the SMPTE specification in the audio field is 30 frames per second, but the SMPTE specification in the video field is 29.97 frames per second. Of course, the error in this can be ignored. But let's calculate:

SMPTE 30frs VS SMPTE 29.97frs

1 hour = 3600 seconds * 30 frames per second = 108000 frames per hour

1 hour = 3600 seconds * 29.97 frames per second = 107892 frames per hour

(i.e. a difference of 108 frames per hour)

As indicated above, the hourly video is actually 108 frames behind the audio, but the audio and video we see are synchronized. In fact, in actual operation, these 108 frames are actually discarded (SMPTE NON-DROP mode). But the audience doesn't know it. Here, the difference of 0.03 frames per second can be ignored, but if it is 23.97 frames per second and 120 frames per second, the loss will be more. Therefore, a breakthrough calculation method is needed.

Contents of the invention

The object of the present invention is to provide a calculation method suitable for audio and video time format conversion in order to solve the above problems.

The present invention achieves the above object through the following technical solutions:

The present invention comprises the following steps:

(1) Load media files;

(2) Read the actual playing time;

(3) The video unit time is unified to make a cut of 1 billion copies;

(4) Round up to get the same frame number;

(5) Get 10-digit precision time;

(6) Convert to standard SMPTE format time.

The beneficial effects of the present invention are:

The present invention is a calculation method suitable for audio and video time format conversion. Compared with the prior art, the present invention has the following advantages: support commonly used formats, support various frame rate files such as 23.97, 29.97, 60, 120, etc. Playing audio and video files can be supported, all playable audio and video files can be output at the same time, and the time code of the same specification can be synchronized. This calculation method can be used in all playback platforms, accurate to 1/1000000000 seconds, the accuracy is greatly improved, and it is easy to use , has the value of popularization and application.

Detailed ways

The present invention will be further described below:

The present invention comprises the following steps:

(1) Load media files;

(2) Read the actual playing time;

(3) The video unit time is uniformly cut into 1 billion copies; (ie: 0.0000000001 seconds, and this number is the time and position value directly extracted from the film itself, so it will not be disturbed by video playback such as stuck frames, regardless of the video playback frame rate. , but there is one thing in common, that is, the unit playback time is the same, that is, seconds).

(4) Round up to get the same frame number; (ie: 25frs or 24frs standard hexadecimal time)

(5) Get 10-digit precision time;

(6) Convert to standard SMPTE format time (ie: hh:mm:ss:ff format time).

In this way, audio and video files with different frame rates can be mixed and cut. No matter how many peripheral devices there are, it can be precisely synchronized; another: SMPTE is accurate to 1/25 second, but this method can be accurate to 1/1000000000 second, the accuracy is greatly improved, and the pros and cons can be seen at a glance.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements are possible, which fall within the scope of the claimed invention. The protection scope of the present invention is defined by the appended claims and their equivalents.

Claims (1)

1. computational methods that are applicable to audio frequency and video Time form transformation, is characterized in that, comprise the following steps:

(1) be written into media file;

(2) read actual play time;

(3) units of video time unification is done the cutting of 1,000,000,000 parts;

(4) round up and obtain an identical frame number;

(5) obtain 10 precision times;

(6) be converted into the standard SMPTE form time.