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Ritek Mini CD-R: Part 2

Ritek Mini CD-R: Part 2

Hi everyone,

Today, I burned a few more Ritek Mini CD-R media, where I found out they have a surface issue:

Ritek CD surface issue 2

I didn’t realized this, but it seems to be a plant manufacture problem. I opened another of the 100-pack I have and it have the same problem.

The problem is that the data was burning fine, with no errors on my Lite-On iHAS524, but it failed to verify on some parts of the disk, as it was approaching the end. I was burning them at 24x, the maximum speed it supports on the writer.

I decided to use the Optiarc AD-7561A drive I have to see if it would burn fine with it, since slim drives usually burns at a lower speed.

M Way External DVD Drive - Colorful Flame Pattern - Teardown - 10
Optiarc AD-7561A

When the CD is inserted in this drive, it is detected as a 10x media:

I burned the CD with this drive, where it was able to both burn and verify successfully. It also seems that the drive burned surface is a bit darker than with the LiteOn drive, so maybe that makes it handle the bad surface better.

Quality tests

I burned 2 CD’s with the Lite-On drive where both burned successfully but didn’t read fine. One was able to read completely, but lowering the read speed at the bad section. The other one failed with unrecoverable errors.

Let’s see their quality tests with the LiteOn drive first, followed with the Optiarc drive:

CD #1 – LiteOn

This is the CD that was able to read completely but lowers the speed. When playing it back, it pauses while reading the wrong area. It can be ripped, but will struggle in the bad area. The ripped file appears to be fine, but EAC reports timing problems. Listening to the track didn’t revealed any issues.

You can see the excesive amounts of C1 and C2 errors.

CD #2 – Optiarc

Here is another burn of the same data, burned with the Optiarc drive and tested on the LiteOn drive. You can see that it only reports a maximum of 10 C1 errors and no C2 errors. The quality score is 99%. Same media, but burned on a different drive, at 10x speed.

CD #3 – LiteOn

This CD failed to test properly. Once again, you can see the excessive amounts of C1 and C2 errors. The positions of the C1 and C2 errors seem to match the ones of the previous LiteOn burn.

CD #4 – Optiarc

Here is another burn of the same data of the previous burn. You can see this time it was successful, with only a maximum of 8 C1 errors and a total of 19. Again, the quality score is 99%, which is the same as the other Optiarc-burned media.

Conclusion

As seen from the above tests, it seems the Optiarc AD-7561A drive can successfully burn these discs if we intend to use all of its capacity. Maybe it is because of the slower burning speed, or because the optical laser can burn them better than the one on the LiteOn drive.

The LiteOn drive can only burn these CDs at 16x and 24x, while the Optiarc can only burn them at 10x. I’ll test burning a disc at 16x at a later time and see if it works. If not, I’ll continue using the Optiarc drive, which has proven to burn them correctly and without any issues.

Distributed AV1 Video Encoding

Distributed AV1 Video Encoding

Hi everyone,

Yesterday, I began working on writing code to encode video files to AV1 in a distributed computing fashion using my private BOINC server. I wrote some PHP code and developed a Windows Forms software that will submit the video files to the distributed computing server so that it can send jobs to connected machines.

The encoding software I’m using is rav1e. This software is currently single-threaded, which means that encoding videos will take some time, especially when using the –speed 0 flag, which is the slowest mode available nut gives the best quality.

My solution at this time consists on splitting the video files into 1-second segments and then launching a rav1e encoding task for each part, each in one CPU thread. This significantly speeds up the encoding process because it can simultaneously encode several parts depending on the CPU being used. For example, if we split a video into a 1-second segment, and you have an AMD Ryzen 7 2700X CPU, this means that you can process 16 seconds at a time.

Preparing the input video file

As I mentioned at the start, I wrote a Windows Forms software that will handle the video submission process. The software will first call ffmpeg to split the video into 1-second segments, extract the audio file and encode it to Opus using the desired bitrate, and then it will submit the 1-second segment video files to the BOINC server, generating a task for each file:

av1_task_submitter

I’m submitting the video files using a quantizer setting of 175 and a speed of 0.

Once the tasks are generated, comes the processing.

AV1 encoding:

The BOINC client is the software responsible for contacting the server to retrieve the splitted files and initiate the tasks. It will download the rav1e executable from the BOINC server, the input video file, and will start the encoder. This process takes about 2 hours and 30 minutes on an AMD Ryzen 7 2700X CPU while for my Intel i7-3610QM and 4700MQ it took more than 3 hours. Still, the advantage is that I get to encode multiple segments at once, speeding the encoding of the source video significantly.

Here, you can see the encoding tasks from 4 of my machines:

rav1e BOINC Tasks
rav1e BOINC Tasks

Result files:

Once the encoding tasks are finished, they are sent back to the BOINC server which will mark the task as completed and will move the results to a defined folder:

.ifv segments
.ifv segments

Merging the files:

The final step is to merge the result files and also merge the audio file. For this, I wrote a simple bash script that calls ffmpeg’s concat function and then merges the concatenated file with the audio to generate one final .webm file. WebM is s container compatible with AV1 video files as well as Opus audio tracks:

Script to merge the .ifv files into the final .webm file
Script to merge the .ifv files into the final .webm file

The script takes 3 arguments. The first one is the list of files to concatenate, the second is the Opus audio file and the third and final one is the name for the output file.

When we run it, we should see the following at the end:

The merging script after running
The merging script after running

The final file:

We can see the final encoded .webm file at the location we typed when we ran the above script:

The final .webm file
The final .webm file

We can also check the file using MediaInfo:

Mediainfo
Mediainfo

And that’s it! BOINC is really useful in this case as I can encode multiple files and the server will handle all of the processing. The only manual part is where we run the merging script to generate the output file. However, it really speeds encoding by a lot. This is, until rav1e becomes multithreading, at which point, he BOINC server can still be used by changing the app to a multi-threading one.

Hope you enjoyed reading this post!

rav1e AV1 encoding tests – 10/15/2018

rav1e AV1 encoding tests – 10/15/2018

Hi everyone,

Today, I’ve been performing some AV1 encoding tests using the rav1e encoder.

You need an AV1-compatible web browser to see the videos below.

The following videos were encoded using speed 10 and different quantizer settings to compare the quality. rav1e is in constant development so I’ll be performing lots of tests. The following uses the appveyor build from yesterday. I’ve managed to install the dependencies needed to build myself rav1e when new commits comes out, so expect my own builds and more video tests from me!

The original video is a Mario Kart 8 Deluxe clip that I captured using an AverMedia U3 capture card and using OBS with the H264 lossless profile. This video was then converted to y4m using ffmpeg and lastly processed using rav1e.exe.

–quantizer 200 -s 10

–quantizer 175 -s 10

–quantizer 160 -s 10

–quantizer 150 -s 10

Notice that the lower the quantizer setting, the better the footage is. These videos were all using the speed 10 quality setting. I’m currently encoding using the default speed of 3. I’ve tried using speed 0 too but it is insanely slow!!! I’ll try to run an encoding to test but it will take some time. rav1e.exe is currently single-threaded.