Transcoding optical media in Linux

Obstacle Course

Queue

If you want to rip several tracks as transcoded single files from a medium to a mass storage device, HandBrake offers the Add To Queue icon in the buttonbar. To begin, select a single track and configure the transfer. Pressing the Add To Queue button sends the job, and the matching configuration, to the list of transcoding tasks to be executed. You can view the tasks by pressing the Queue icon. If necessary, you can also remove tasks from the list.

If you want an overview of an existing task, press the Preview icon in the buttonbar. HandBrake now opens a small preview window in which it displays a short sequence of the selected track with the individual settings, so you can assess whether the configuration needs more tweaks.

Once the queue is ready, HandBrake begins processing when you press Start . The application then displays how the transcoding is proceeding in a progress bar at the bottom of the program window. The bar also shows the progress as a percentage and chronologically in real time.

Hardware

HandBrake leverages various capabilities of modern processors that address multimedia optimizations. The software supports various streaming SIMD extension (SSE) standards [7] for Intel processors, as well as the Quick Sync video processor available as of the Sandy Bridge Intel generation [8]. These settings often accelerate significantly the speed at which video formats are encoded and decoded.

If you use a dedicated Nvidia graphics card in your computer system, depending on the model, you can use Nvidia's Nvenc technology. In combination with HandBrake, this noticeably accelerates hardware encoding of H.264- and H.265-encoded videos. You can find which Nvidia GPUs work with Nvenc by checking the software documentation [9]. Note that not all Linux distributions support Nvenc, and you need to install it separately [10].

The CUDA Nvidia acceleration technology is not supported, nor for its AMD counterpart. Basically, however, HandBrake works with all common processors from the Intel Core 2 Duo generation and from the AMD Athlon X2. Because the software scales well to multiple cores, a system with four or six cores will be faster than a dual-core CPU.

Nevertheless, processing a Blu-ray disc with a high resolution and frame rate quickly pushes older computer systems to their limits. In such scenarios, transcoding with older Core i5 or i7 processors takes two or more hours at full system load, given a normal movie length (Figure 4).

Figure 4: HandBrake stresses older systems.

High-resolution Blu-ray media require a large amount of space, even in a transcoded state. Whereas a video DVD transcoded in PAL format usually occupies between 1 and 2GB of storage space, you have to allow between 30 and 50GB for a video Blu-ray. The space requirement can be significantly influenced by the resolution of the target file. Audio and subtitle tracks, on the other hand, do not have a major influence on the overall size.

Logged

Damaged media slow down transcoding enormously from error correction runs. Therefore, it can be very useful to pinpoint problems. To this end, HandBrake offers a window with a history log, which you can access by pressing the Activity button in the buttonbar. The log (Figure 5) provides data about the original storage medium, the content, codecs, file formats, and computer hardware.

Figure 5: From the history log, you can trace faulty transcoding processes.

The log will indicate missing system libraries that make it impossible, for example, to include menus on the Blu-ray disc. The protocol can therefore be used to identify and eliminate the causes of errors. Another click on Activity closes the log.

If you want to interrupt the data conversion process, press the Pause icon, which toggles to a Resume icon, which you can press to continue converting.

HandBrake also reports potential storage problems when starting the transcoding process. It calculates the anticipated storage requirements for the transcoded file and compares it with the free space on the target medium. The software preempts interrupts during conversion, in which case, you should outsource existing data.

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