Summary of embedded audio and video doubts

In a small head, there are big questions. This article is mainly for chatGPT learning notes after bloggers encounter problems at work.

1. What is bypass hdr?

" " refers to a setting that Bypass HDRbypasses the HDR ( ) function. HDRHDR refers to a display technology that can provide higher color depth and brightness range, resulting in more realistic, bright and layered images. In some cases, users may choose to disable the HDR feature, such as when they are watching content that does not support HDR, or when using certain applications and need to disable HDR for better performance. Therefore, " Bypass HDR" is a setting option that allows users to enable or disable the HDR function.

Video pass-through is a bridge function for the AV amplifier to connect the video source and the display device, the video is bypassed, and the audio is left for decoding.
If the passthrough version is not high enough, the backend display device will be limited.

2. What is the AP side?

The AP ( ) side refers to the main processorApplication Processor in smart mobile devices such as mobile phones and tablets , also known as an application processor . It is responsible for running the operating system and applications and is one of the core components of the device . AP is usually composed of ARM-based chips, including , , , and so on. In a smartphone, the AP side is usually composed of a high-performance multi-core processor, GPU, and large-capacity memory to ensure that the device has a fast response and a smooth user experience.CPUGPU内存控制器外围接口

3. What is setprop log.tag.OMX V?

setprop log.tag.OMX Vis an Android command that sets the logging level . In this command, log.tag.OMXis the log label , which Vrepresents the log level , where Vmeans the lowest log level (even if all log messages are logged).

Therefore, running this command will enable verbose logging for OMX components .

4. What is the DVO mode in multimedia?

DVO stands for Depth Video ObjectDepth Video Object .

This is a 3D representation that combines RGB color images and depth images, and it can be used in applications such as object detection, tracking, and segmentation .
By using depth information, DVO can more accurately identify objects in the scene and perform finer manipulation and control over them.

5. [VO] What does DumpInfo dtg_omxDelay=0 mean?

OpenMAXThis sentence indicates the debugging information of the video codec or other media processing software using the OMX ( ) standard. Among them, "[VO]" may refer to the abbreviation of Video Output.

" dtg_omxDelay=0" means OMX delay is 0 , OMX is an open, cross-platform media processing framework, which can be used to realize the codec, processing and transmission of multimedia data such as audio, video and images in mobile devices and embedded systems and other functions. OMX components exchange media data through buffers, so there is a concept of delay in OMX.

The " " here dtg_omxDelay=0means that in this video output component, the delay of OMX is set to 0, that is, the delay between OMX components is reduced as much as possible to improve the response speed and smoothness of video output.

6. What is VSC Control?

VSCControlMay refer to a module or driver that controls video output in an embedded system.
It may provide some APIs or commands for setting video output parameters, switching video sources, adjusting resolution, etc.

Specifically, VSCControlthe following functions may be included:

1. Control the connection of video input and output , such as selecting different video sources, switching input channels, setting output resolution, etc.
2. Provides control of visual effects such as full-screen display, screen zoom, and screen rotation .
3. Support audio output control , such as adjusting volume, selecting different audio output devices, etc.
4. Supports decoding and encoding of multiple video formats , as well as corresponding image processing and rendering functions.
5. Provide an interface for interacting with the operating system and external devices , such as outputting video to an external display through the HDMIor interface.VGA

It should be noted that VSCControl may have different implementation methods and functions in different embedded systems.

7. What is ts stream?

TS stream, called transport stream ( Transport Stream), is a format for digital video broadcasting and storage . It is a container format defined in the MPEG-2 standard, which can mix multiple audio, video, data and other elements in one data stream for transmission or storage .

In the TS stream, each video, audio or other data stream is divided into small packets ( Packet), each packet has a fixed size of 188 bytes, of which 4 bytes are synchronization bytes , so that the receiver can correctly parse the data stream . Each packet also carries some control information, such as packet type, PID ( Packet Identifier), etc., to help the receiver process and decode the data.

TS stream is mainly used in scenarios such as digital TV broadcasting, webcasting, and video storage . It has the advantages of high transmission efficiency, good fault tolerance, and strong reliability , so it is widely used.

8. What is the difference between 2k avc (omx) and 4k hevc (Esticker)?

2k avc(omx)and 4k hevc(Esticker)are two different video formats.

2k AVC ( Advanced Video Coding) is a standard high-definition video encoding format, usually used for movies with a resolution of 2048×1080 or 2048×858 . It uses an advanced video compression algorithm, which can greatly reduce the file size while ensuring the image quality, thereby improving the transmission efficiency.

4k HEVC ( ) is also a video encoding format, which has higher resolution and higher compression efficiencyHigh Efficiency Video Coding than 2k AVC . It can support up to 7680×4320 pixel video resolution, and can reduce the video file size to about 50% of the original, while ensuring high-quality video playback. Since 4K is an ultra-high-definition resolution , it requires higher-end equipment to play it.

9. What is the problem with Decrypt error?

" " error occurred Decrypt error. This could be due to one of the following reasons:

• Encrypted data has been corrupted : Please check that the encrypted data is intact and has not been tampered with.
• Wrong key or key mismatch : Please check that you are using the correct key and make sure it matches the encrypted data.
• Wrong encryption algorithm : Please make sure to use the correct encryption algorithm for decryption.

10. AddKey failed, Decrypt failed, and the underlying DRM check failed

DRM has AddKeyfailed and Decryptfailed errors. The root cause of the DRM failure needs to be checked. It is recommended to check the following areas:

• Check whether the network connection is normal and make sure the DRM server is available.
• Check that the key request is correct, it may be necessary to update the key request.
• Check whether the time and time zone settings of the device are correct, and ensure that the device time is consistent with the DRM server time.
• Check whether the DRM certificate has expired or been revoked, and the certificate needs to be renewed.

If the above methods cannot solve the problem, it is recommended to contact the technical support team of the DRM provider for further investigation and solution.

11. What is DRM?

DRM is an acronym for Digital Rights Management, which is a technical means designed to protect the copyright of digital content. It uses methods such as encryption, authorization and access control to ensure that digital content can only be used by authorized users and prevent unauthorized copying, distribution and modification.

Digital rights management technology can be applied to various digital contents, such as music, movies, software, games and so on. It usually consists of two main components: encryption and decryption. Encryption converts digital content into an unreadable format that only authorized users can decrypt and use. Among them, decryption requires corresponding keys, which are provided by the authority and are only authorized to specific users or devices.

In short, DRM technology is an important support for the digital content industry, which can effectively protect the copyright of digital content and safeguard the legitimate rights and interests of digital content creators and copyright owners.

12. What is MPB_DRM

MPB_DRMIt can be applied to the protection and management of various digital contents. Embedded multimedia devices usually have functions such as storage, playback, and recording, so a safe and reliable digital rights management technology is needed to protect the digital content contained therein.

For example, in the field of mobile smart terminals, MPB_DRMit can be used to protect the copyright of digital content such as music, e-books, and videos. When users purchase these digital contents, they must be authenticated to obtain the corresponding key for decryption, so as to ensure that only authorized users can access and use these contents.

In car entertainment systems, MPB_DRMit can also be used to protect the copyright of digital audio and video. Through encryption and authorization, MPB_DRMunauthorized copying and distribution can be prevented, thereby effectively protecting the copyright of digital content.

In short, MPB_DRMas a digital copyright management technology, it has broad application prospects in the field of embedded multimedia, which can effectively protect the copyright of digital content and promote the healthy development of the digital content industry.

13. What is the two-way decoder?

Two-way decoder refers to a multi-channel video decoder that can decode two video streams at the same time . This kind of decoder is usually used in video conferencing, surveillance systems, broadcasting and television, etc. where multiple video streams need to be processed simultaneously.

The two-way decoder achieves fast and efficient decoding by processing two video streams in parallel , thus ensuring that each video stream can be processed and displayed in a timely manner. In addition, the two-channel decoder can also support multiple video codec formats, including H.264, MPEG-4, VC-1, etc., to meet the needs of different application scenarios.

When using a two-way decoder, you need to pay attention to the limitation and allocation of hardware resources. Since decoding is computationally intensive, sufficient processing power and memory capacity are required to support parallel decoding. In addition, in order to avoid unnecessary interference and conflicts, the two-way decoder also needs good operating system and driver support to ensure stable and reliable operation.

In short, the two-channel decoder is a powerful and comprehensive multi-channel video decoder , which is suitable for various application scenarios that need to process multiple video streams at the same time.

14. What is the white list?

A whitelist ( white list) is a network security mechanism used to limit the resources that a system, software, or service can access or perform. It is an allow list, only resources or operations listed in it can be accessed and performed, and other resources or operations not listed are denied or blocked.

The whitelist mechanism is usually used in security software such as antivirus software, firewall, and network filtering. For example, antivirus software can establish a whitelist mechanism to specify which files, programs, processes, ports, etc. are legal, thereby preventing malicious software and virus attacks.

Additionally, whitelisting mechanisms are also widely used in corporate networks to control which applications and websites employees can access and use. Administrators can formulate corresponding whitelist rules according to company policies and security requirements, and only allow employees to access and use applications and websites listed in the whitelist, so as to achieve the purpose of managing and controlling the corporate network.

In summary, the whitelist mechanism is an effective means of network security control that can help protect systems and networks from unauthorized access and attacks.

15. What is the cast whitelist?

Google CastWhitelisting refers to a network security mechanism that restricts the apps or services that a Google Cast device can send content to. Google Cast is a streaming media transmission protocol that allows users to send audio, video and image content through mobile phones, computers and other devices to devices that support the Google Cast protocol for playback.

In order to ensure the security and stability of Google Cast devices, the Google Cast whitelist mechanism establishes an allowed list, only the applications or services listed in it can communicate with and send content to Google Cast devices, other unlisted applications or Service is denied or blocked.

The Google Cast whitelist mechanism can help prevent Google Cast devices from unauthorized access and attacks, and improve device security and stability. Additionally, the Google Cast whitelist will make it easier for developers to test their apps to ensure their compatibility and interoperability with Google Cast devices.

In conclusion, the Google Cast whitelist is an effective network security mechanism that can help protect the security and stability of Google Cast devices, and it is also beneficial for developers to test and optimize their applications.

16. What is VBM?

VBM is Virtual Battery Managementan acronym for Virtual Battery Management . It is a technology for simulating and managing the battery state of mobile devices.

In mobile devices, battery life is often one of the top concerns for users. In order to better manage and extend battery life, many systems and applications provide battery management functions. Among them, VBM technology can predict and manage the power consumption of devices by simulating parameters such as battery power, temperature, and health status.

Specifically, VBM technology can predict the battery consumption of the device in the future based on the current usage and settings of the device, and adjust the power management strategy of the device based on these prediction results to extend the battery life as much as possible. In addition, VBM technology can also automatically reduce device performance or enter power saving mode when the battery power is too low or other abnormal conditions, so as to ensure the stability and reliability of device operation.

In short, VBM is a virtual battery management technology that can help mobile devices better manage and extend battery life, and improve device operating efficiency and stability.

17. What is M2TS?

M2TS is a video file format, the full name is " MPEG-2 Transport Stream". It is a high-definition video transmission format based on the MPEG-2 standard, and is usually used to convert high-definition television signals and movies on Blu-ray discs into digital formats for preservation. The M2TS file format typically contains multiple audio, video, and subtitle streams, and can support video at up to 1080p resolution. In addition, M2TS files are also widely used in the production and storage of Blu-ray discs.

18. What is workaround?

Workaround refers to a stopgap or temporary solution . In the field of software development and IT, Workaround is usually used to describe some temporary solutions to avoid certain problems from affecting the normal operation of the system or application.

Workarounds are usually a temporary measure in the absence of a better solution or fix. For example, when a software has a vulnerability or bug but has not been officially fixed, users can use Workaround to reduce the impact of the vulnerability or bug on themselves. Workaround may involve modifying configuration files, using third-party tools, adjusting system settings, etc.

It should be noted that Workaround is only a temporary solution, not a final solution. Workarounds should be canceled or modified as soon as the relevant issues are formally fixed or upgraded.

19. What is the difference between hevc and avc?

HEVC and AVC are two video coding standards, also known as H.265 and H.264. The main difference between them is compression efficiency .

HEVC uses a more advanced algorithm to compress video, making the video file smaller under the same image quality, and the **compression rate is more than 50%** higher than AVC. This means that for the same video quality, encoding with HEVC can save more storage space or bandwidth. In addition, HEVC also supports higher resolution video, such as 4K, 8K, etc.

However, since HEVC's compression algorithm is more complex and requires higher computing power, it requires more hardware resources in encoding and decoding, and the decoding speed is slower. At the same time, HEVC also requires specialized hardware support to take advantage of its advantages, which makes the popularity of HEVC relatively slow.

In short, the difference between HEVC and AVC lies in the compression efficiency and the required hardware resources. Which standard to use depends on the actual application requirements and device support.

20. What is the 3GP format?

The 3GP format is a video file format for mobile phones, and its full name is " Third Generation Partnership Project". It is a multimedia container format based on the MPEG-4 standard, mainly used to play and transmit video files on mobile devices. The 3GP format can store various types of data such as audio, video, and text, and usually has a small file size, which is suitable for transmission in an unstable network environment or limited bandwidth. In addition, the 3GP format also supports streaming, allowing users to download and play simultaneously without waiting for the entire file to be downloaded. Due to its high compression and portability, the 3GP format has become one of the main standards for mobile phone video files.

21. What is the difference between MKV and MKA?

Both MKV and MKA are common audio and video file formats. The differences between the two are as follows:

1. MKV format
   The full name of MKV is " Matroska Video", which is an open, free and universal multimedia container format. The MKV format can store multiple types of data such as audio, video, and subtitle streams, and can be compressed using various encoding methods. The MKV format usually has high picture quality and sound quality, and supports functions such as multiple audio tracks and subtitles , so that users can freely switch or choose different language versions.

2. MKA format The
   full name of MKA is " Matroska Audio", which is a multimedia container format that only contains audio. Similar to MKV, the MKA format is also an open , free, and universal format that can store multiple audio streams and support various encoding methods for compression. The MKA format is usually used to store high-quality audio files, such as lossless audio files or DTS audio tracks .

To sum up, the MKV format is a general-purpose multimedia container format that can be used to store various types of data such as audio, video, and subtitles; while the MKA format is a container format specially used to store high-quality audio files. Contains only the audio stream.

22. What is the difference between ASF, WMV, and WMA?

ASF, WMV and WMA are all audio and video file formats developed by Microsoft Corporation. The differences between them are as follows:

1. ASF format
   The full name of ASF is " Advanced Systems Format", which is a container-based multimedia file format. The ASF format can store multiple types of data such as audio, video, and subtitles, and supports various encoding methods for compression. The ASF format is usually used for network transmission and streaming media playback, and has better data transmission and real-time performance.

2. WMV format
   The full name of WMV is " Windows Media Video", which is a video file format widely used on the Windows platform. The WMV format usually uses Microsoft's own video encoding technology, which can provide better picture quality at a relatively small file size. The WMV format also supports Digital Rights Management (DRM) technology, enabling users to better protect their copyrighted content.

3. WMA format
   The full name of WMA is " Windows Media Audio", which is an audio file format widely used on the Windows platform. The WMA format usually uses Microsoft's own audio coding technology, which can provide better sound quality with a relatively small file size. The WMA format also supports Digital Rights Management (DRM) technology, enabling users to better protect their copyrighted content.

To sum up, ASF, WMV and WMA are all audio and video file formats developed by Microsoft, they are respectively used for storage and transmission of multimedia containers, video files and audio files, and all support digital rights management (DRM) technology.

23. What is the difference between MPG and MPEG?

Both MPG and MPEG are common video file formats, and the differences between them are as follows:

1. MPG format
   The full name of MPG is " Moving Picture Experts Group", which is a container-based video file format. The MPG format is usually compressed using MPEG-1 or MPEG-2 video coding technology, and can store various types of data such as audio, video, and subtitles. The MPG format is usually used to store DVD video, digital TV programs, etc., and has good compatibility and wide application fields.

2. MPEG format
   MPEG is also Moving Picture Experts Groupthe abbreviation of " ", which is a standardized video coding format. The MPEG format is divided into several versions, including MPEG-1, MPEG-2, MPEG-4, etc. The MPEG format is usually compressed using a variety of different video encoding techniques, which can reduce file size while maintaining image quality. The MPEG format is widely used in digital TV, DVD, network streaming media and other fields.

To sum up, the MPG format is a container-based video file format, usually used to store DVD video, digital TV programs, etc.; while the MPEG format is a standardized video encoding format, which is divided into multiple versions and is widely used. Used in digital TV, DVD, network streaming media and other fields.

24. What is OGG?

OGG is an open, free, and free audio file format, its full name is Ogg Vorbis. It is a container-based audio file format that can store information such as audio streams, metadata, and text annotations. The OGG format was originally developed by the Xiph.org Foundation to provide an audio compression technology with higher quality and lower bit rate than MP3.

The OGG format is used Vorbis编码技术for audio compression. This technology can provide better sound quality in a smaller file size, and does not need to pay patent fees. In addition, the OGG format also supports advanced functions such as multi-channel and dynamic range control, making it widely used in games, movies, broadcasting and other fields.

In addition, the OGG format also has a derivative format - OGG Theora, which is a container-based video file format that uses Theora video encoding technology for compression, which can provide better image quality in a relatively small file size. OGG Theora is usually used in network video, online education, digital library and other fields.

In short, OGG is an open, free, and free audio file format that uses Vorbis encoding technology for audio compression, with high sound quality, small file size, and advanced functions.

25. What is HLG?

HLG is a wide color gamut, high dynamic range (HDR) video technology, the full name is Hybrid Log-Gamma. It was jointly developed by the BBC and NHK to provide an HDR video standard suitable for broadcast television.

HLG technology uses a hybrid gamma curve so that video signals can be interpreted by both standard dynamic range (SDR) and high dynamic range devices. This means that videos produced using HLG technology can be displayed with normal brightness and color on ordinary SDR display devices, while on devices that support HDR, they can show a wider color gamut and higher brightness range, thus Obtain a more realistic and vivid picture effect.

HLG technology has been officially recognized by organizations such as the International Telecommunication Union (ITU) and the European Television Union (EBU), and has been applied in various fields including TV broadcasting, Internet video, and Blu-ray discs.

26. What is the difference between Samsung HDR10+ and ordinary HDR?

HDR10+ is a high dynamic range (HDR) video technology introduced by Samsung Electronics. Compared with ordinary HDR10 technology, HDR10+ has innovations in image processing and coding to provide a better visual experience.

The difference is as follows:

1. Dynamic metadata
   Unlike HDR10, HDR10+ can embed dynamic metadata into each video frame, and adjust parameters such as lighting and color in real time according to the needs of the scene to provide more accurate picture effects.

2. Higher brightness and contrast
   HDR10+ technology supports higher brightness and contrast, which can present brighter, more delicate and more realistic picture effects.

3. Adaptive screen mapping technology
   HDR10+ also introduces adaptive screen mapping technology, which can be optimized according to the characteristics and capabilities of the display device to obtain the best visual effects.

In short, compared with HDR10 technology, HDR10+ has innovations in image processing and encoding, has higher brightness and contrast, and can adjust parameters such as lighting and color in real time according to the needs of the scene, providing more accurate and vivid picture effects.

27. Are HDR10 and 2k the same?

no the same. HDR10 is a high dynamic range technology used to provide a wider range of brightness and color to produce richer, more realistic images. And 2K is a resolution standard, referring to an image with a horizontal resolution of about 2000 pixels. The two are not directly related and can be used together or separately.

28. What is image.pftrace?

Based on the filename "image.pftrace" you provided, I cannot determine the exact type or content of this file. Generally speaking, the file extension ".pftrace" indicates that this is a trace data file generated by the pftrace tool, which contains captured network packets and corresponding metadata.

The ".image" extension may indicate that this is an image file, which can be a disk image or a memory image file. Therefore, "image.pftrace" may be an image file generated by the pftrace tool, which contains captured network data and metadata information.

However, the exact file type depends on the actual content and purpose of the file, and further analysis is required to arrive at an accurate answer.