Now access to the Internet is available on almost all mobile phones, tablets, and desktop computers. Every day, millions of users, using various devices, watch the video on the Internet in real-time or in recorded form. However, in such a situation, the problem arises that different devices have different technical characteristics, bandwidth, and connection speed. Depending on this, video files need to be created with different formats and qualities for different users.
Transcoding is a process that allows the conversion of video and audio files from one format to another, thereby creating a format suitable for the end-user. In this article, we will explore what transcoding is, its main benefits, why it is needed, and why it is crucial for video streaming. We will also learn how video transcoding works and how you can transcode your video files.
What is transcoding
Transcoding is the process of receiving an encoded video or audio file, decompressing, modifying, and recompressing it. For example, video for live streaming can be transcoded from its original format to multiple-format streams that are delivered to the largest number of viewers on the widest range of devices.
Difference between encoding and transcoding
Video encoding is the process of making raw video files smaller using compression. Transcoding is the process of unpacking a file from one codec and then encoding it into another one. Encoding only happens when the video is recorded for the first time. Otherwise, it is usually a transcoding from one format to another.
Transcoding vs transmuxing vs transrating
Transmuxing is the process of changing the delivery format for video and audio without encoding or transcoding the original content. Transmuxing is a fairly common content delivery procedure. It differs from transcoding in that during the transcoding process some changes are made to the file after it has been unpacked.
Transrating is the process of changing the video bitrate. In this case, the video content, video format, and codec remain unchanged, and only the bit rate changes. For example, you can lower the bitrate from 8 Mbps to 4 Mbps so that the media can be streamed at a lower bandwidth. We can say that transrating is a kind of transcoding.
Files types and formats in video transcoding
Video transcoding works using a video codec. A video codec is a device or software that compresses video files. It removes redundant data from the file while trying to keep the file in the best possible quality. Let’s take a look at the most popular video codec types.
- MPEG-4. It is a well-known format created for storing video information that has been compressed using the MPEG-4 algorithm. MPEG-4 is an international standard that has been approved by the international organization of experts ISO, and is considered one of the most common among its counterparts. It is used in the process of recording films, in the field of video telephony, as well as in broadcasting.
- HEVC/H.265 uses more efficient video compression algorithms compared to H.264/MPEG-4. It is designed in response to the growing demand for higher compression rates for moving images for a variety of applications such as Internet streaming, data transmission, video conferencing, digital storage, and broadcast television.
- VP9 is a video compression format and video codec developed by ON2 Technologies, which was acquired by Google.
A video format is a type of file format for storing digital video data on a computer system. Video is almost always stored using lossy compression to reduce the file size. List of the most popular file formats:
- MP4 is the most widely used format. It is supported by all browsers and video players.
- QuickTime File Format is Apple’s multimedia format.
- FLV. It used to be a very popular format. Its popularity has declined now as it requires a plugin to play the video, and this feature is not required for the HTML5 video component.
- WebM is an open-source Google video container format.
- Advanced Systems Format is a Microsoft video container format specially designed for video streaming.
Why is transcoding needed? Why is it important?
Video transcoding is very important when you want your content to be available to more end-users.
Let’s take a look at the most important reasons for using transcoding.
When you use a format such as HLS, it allows the video player to dynamically switch between video sources based on the viewer’s Internet connection and device. For example, switch between 1080p and 720p versions of the video stream.
Transcoding allows you to generate various video sources required for ABR from single video input. This is great for people streaming live from environments with limited download speeds.
Transcoding also allows a stream to be transcoded into several formats, such as HLS or MPEG-DASH. This is useful when streaming to a range of devices that support different formats.
Custom transcodes for different directions
Streaming to multiple platforms means the platforms would have different video input requirements. For example, Periscope recommends an input resolution of 540p. Instead of downsizing all the streams to 540p, the original video can be re-encoded to a separate, lower-resolution stream used only by Periscope.
How does transcoding work
The transcoding process includes several stages:
- Decoding the original video file into an intermediate uncompressed format.
- Conversion/scaling of the received content.
- Transcoding it into target format.
All this can be done using special software, which is discussed in more detail below in this article.
Benefits of using video transcoding
Video transcoding is important for both, the publishers and the end-users. Let’s look at the main benefits for both parties separately.
Benefits for publishers:
- Reduces the cost and complexity associated with encoding multiple resolutions and bitrate options.
- Removes playback restrictions based on codecs, protocols, and configurations available in the encoder.
- Provides the ability to use new generation technologies.
Benefits for users:
- Lack of buffering due to low bandwidth connections.
- The ability to receive video in the format and resolution supported by the device.
- The ability to receive high-quality video for users with the best connectivity and resolution.
Drawbacks of transcoding
Transcoding requires significant hardware and system resources. It runs very slowly on devices with less RAM and a low-performance processor.
Quality reduction is another very important disadvantage for lossy formats. Compression artifacts accumulate, so transcoding causes a progressive loss of quality with each successive generation, known as digital generation loss.
Why is it critical to use video transcoding for streaming?
If a live video is broadcast without using transcoding, we can run into several problems. First, viewers without sufficient bandwidth will not be able to view the broadcast. Their players will constantly buffer. Secondly, without video transcoding and conversion, users who have devices with low connection speed (tablets, mobile phones, and connected TV devices) will not be able to view the video broadcast.
Using a transcoder software or service, we can simultaneously create a set of time-synchronized video streams, each with a different bit rate and frame size, converting codecs and protocols to reach additional viewers. This set of streams can be packaged in several adaptive streaming formats so that they can be played on almost any device.
How can you transcode your video?
Transcoding can potentially occur via software on any PC or laptop, on a dedicated media server, or on a SaaS platform. However, it benefits from significant hardware and computer resources such as large amounts of system RAM, graphics acceleration, and high-performance processors. Transcoding HD video for editing in traditional video production (corporate video, television, etc.) can take hours even for powerful computers.
There are different types of video transcoders. They can be an open-source software with a command-line interface or a program with advanced features and user interface. Also videos can be transcoded locally or in the cloud.
Local transcoding involves using the video editing and compression software installed on the system. Cloud transcoding allows the video file to be uploaded to the cloud, set up options for the file, thus re-encoding it in different available versions.
Let’s consider the main advantages and disadvantages of both approaches local and cloud video transcoding.
- Works slower.
- Creates a separate file for each version that needs to be uploaded and processed separately.
- Requires installation of video transcoding software on the system.
- No subscription fees. Pay for the software, install it, and get started with no additional fees.
- Works quickly and conveniently. Simply upload the file to the cloud platform and select parameters for the file, and the platform will re-code it into the required number of versions.
- No need to install software as all transcoding is done in the cloud.
- A subscription fee for using the cloud infrastructure is possible.
What is a codec? Examples of Video codec
A codec is a device or computer program that encodes or decodes data or a signal. Example video codecs: Cinepak, MPEG-4, H.264, VP8.
How long does it take to transcode video?
Transcoding time depends on the tool you use. It is typically 1:1 or even faster. It means one hour of source video file takes about one hour or less to transcode.
In this article, we looked at what video transcoding is and why it should be used in order to deliver video content to as many users as possible. Gumlet offers simple and convenient video transcoding tools. Choose the transcoder that is right for you and process your video so that it is accessible from any device in the world.