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• Increased File Size When Converting MP4 to WebM using FFmpeg

  23 décembre 2024, par kimgijeong

  I am using FFmpeg to convert MP4 to WebM with the following command :

  


  ffmpeg -y -hide_banner -nostats \
-f mov,mp4,m4a,3gp,3g2,mj2 -i "http://127.0.0.1:80/lotteon-low-bitrate.mp4" \
-threads auto -f webm -acodec libopus -b:a 96.059k -vcodec libsvtav1 -preset 11 -pix_fmt yuv420p \
-vf "scale='min(-1, iw)':'min(-1,ih)':force_original_aspect_ratio=decrease,crop=trunc(iw/2)*2:trunc(ih/2)*2" \
"/usr/local/m2/m2temp/xcdrtmp/2052_1.webm"


  


  However, the output webm file size is larger than the source MP4 file. For example :

  


  


  • Source MP4 : 4.6 MB (bit rate : 994,053 bps)

    


  


  • Output WebM : 16 MB (bit rate : 3,902,037 bps)

    


  


  


  I know SVT-AV1 encoder defaults to CRF mode. Due to not specifying the bitrate explicitly, the SVT-AV1 encoder automatically sets the bit_rate. It appears that the encoder is setting it to a much higher value (3,323,104 bps), causing the increase in file size compared to the source MP4 (994,053 bps). Here are the methods i tried to reduce the WebM file size compared to the source MP4 :

  


  

  1. -b:v 994k

  


  


  I tried to match the target bitrate with the source MP4's bitrate to reduce the output size, but encountered the following error :

  


  Svt[error]: Instance 1: Force key frames is not supported for VBR mode Last message r
epeated 2 times [libsvtav1 @ 0x239dd100] Error setting encoder parameters: bad parameter (0x80001005)


  


  Looking at the official documentation, this mode change (from CRF to VBR when setting a target bitrate) appears to be expected behavior. However, the error is puzzling since I haven't set any force keyframe parameters in the FFmpeg command.

  


  

  2. svtav1-params "mbr=994k"

  


  


  The second method i tried was using the svtav1-params "mbr=994k" option to set the maxrate while maintaining CRF mode This method showed some improvement, but the output file size was still larger than the source MP4.

  


  

  • Output WebM : 5MB (bit rate : 1,209,877 bps)

  


  


  The more critical reason why we can't adopt the second method (using svtav1-params "mbr=994k") is that even for the same MP4 source file, the output file size varies slightly with each encoding.

  


  

  3. -b:v 994k -svtav1-params “rc=2:pred-struct=1”(CBR, low delay)

  


  


  The final method I tried was setting the target bitrate while using CBR (Constant Bit Rate) and low-delay mode The default value for pred-structure is 2(random access), but I had to use low-delay mode due to the following error :

  


  Svt[error]: CBR Rate control is currently not supported for SVT_AV1_PRED_RANDOM_ACCESS, use VBR mode


  


  This way was the only approach among those i tried that successfully reduced the output size.

  


  

  • Output WebM : 4.3MB (bit rate : 1,032,373 bps)

  


  


  In summary, I have three questions about this MP4 to WebM conversion issue :

  


  


  1. When setting the target bitrate with -b:v 994k, the switch to VBR mode is expected behavior. However, why does the force keyframe error occur when we haven't explicitly set any force keyframe parameters ?

     


  


  2. Why does the output WebM file size fluctuate when setting maxrate either through -maxrate or svtav1-params "mbr=994k", even when using the same MP4 source file ?

     


  


  3. Besides using -b:v 994k -svtav1-params "rc=2:pred-struct=1" (CBR with low delay), are there any other methods that can guarantee a WebM output size smaller than the source MP4 when converting from MP4 to WebM ?

     


  


  


  I am using a recent version of the SVT-AV1 codec :

  


  Svt[info]: SVT [version]:       SVT-AV1 Encoder Lib 58146ca
Svt[info]: SVT [build]  :       GCC 11.5.0 20240719 (Red Hat 11.5.0-2)   64 bit
Svt[info]: LIB Build date: Oct 28 2024 07:40:59
ffmpeg video svt-av1


  


• ffmpeg : is there a fast way for extracting several thumbnails from a video without parsing the video from the beginning every time ?

  18 mars, par archie

  I tried several ways for extracting sample frames from a video file with ffmpeg. I found out that the fastest way is by placing the following command in a loop :

  


  ffmpeg -ss $frame_time -i "$input_video" -frames:v 1 -vf scale=256:-1 "$Work_dir/thumb$thumb_index.jpg"


  


  (I have omitted the parts of the command that are not relevant to the question, such as drawtext, hide_banner, loglevel). The variables frame_time and thumb_index are initialized before the loop and incremented by a fixed amount at every step : +1 for thumbs_index and $duration/25 for frame_time. I read in the ffmpeg documentation (https://trac.ffmpeg.org/wiki/Seeking) that having the -ss part before the -i part is very fast because the input is parsed by keyframe. For the same reason, the loop containing the command above is also much faster than commands based on "-vf fps=$thumbs_number/$duration".

  


  In fact, the code works pretty well. However, I can't escape a feeling of programming discomfort, because ffmpeg is called several times for each video file, and every time it has to parse the file from the beginning. I mean, if I had a function doing the same as the command above — it would parse a video from the beginning to search for a frame at a certain time — calling it n times to extract a regular sequence of n frames would be bad programming. I should change the function to parse the video file once and get all the frames I need in a single pass.

  


  My question is : is there a fast way for having ffmpeg parse a video file a single time, searching by keyframes and extracting a given number of frames at a given distance from one another ? I am ready to take No for an answer, but one who is deeper into ffmpeg than I am might know a way. Thanks

  


• Piwik is now Matomo – Announcement

  
  9 janvier 2018, par Matomo Core Team

  You may be surprised to read this announcement, but no stress, take a deep breath, nothing big is going to happen, it is just our name that is changing and here are the reasons why.

  

  Why are we changing from Piwik to Matomo ?

  “After an epic 10 year journey creating and perfecting the best open digital analytics solution, we felt it was a good time to refresh our brand to reflect how far we have come and to reaffirm our vision :
  To create, as a community, the leading international open source digital analytics platform, that gives every user full control of their data.”

  Matthieu Aubry, creator of Piwik

  As projects evolve, so do names. After 10 years of Piwik and the amazing achievement of building the top open source analytics software that gives every user full control of their data, we are now looking forward to the next chapter. Thus, Piwik, the community project, will now become Matomo. The only change is our name, everything else stays the same.

  This will allow users to take a fresh look at what we’ve become today and acknowledging all of the community’s hard work over the past 10 years. In addition, we also want our name to be unique, ensuring that it is not shared with any other company to remove any possible confusion or affiliations. Piwik is already used on over 1 million websites and with Matomo, we hope to reach our maximum potential.

  With the strong focus on privacy worldwide and the upcoming privacy regulations about to be legislated in Europe, it is clear that we were on the right mission from the very beginning. With the upcoming big release Matomo 4.0 planned for this year, new privacy protections will bring users the tools to be compliant with the GDPR privacy laws. And Matomo will grow in line with these regulations, with a very clear and focused vision.

  Changing our name is an exciting opportunity for us, and we hope you love the name Matomo as much as we do.

  Matomo FAQs

  So what is going to change for me ?

  Well, basically nothing, the name will change but the values stay the same : Matomo (Piwik) will continue to be free and always will be.

  Also the same people stay behind the project. We are motivated more than ever to take this project to the next level.

  Why not keep the name Piwik ?

  For a few reasons, one of which is to ensure that Matomo does not/will not share its name with any other businesses unlike Piwik. We also want to protect the Matomo brand and for it to remain the open source community project name forever.

  Where does the name Matomo come from ?

  We loved the name Piwik and were looking for something that sounded just as good ! Initially we wanted to have an acronym based on key terms, such as Free, Open Source and Privacy, but none really fit us perfectly.

  Until we found Matomo ! Easily pronounced in all languages. Short enough to remember. Concise. And best of all… Matomo means honesty in Japanese. Which aligns with one of our key values – transparency.

  We love the name Matomo and hope you do too.

  What is the vision of Matomo ?

  

  We have come a long way in those 10 years ! However, our mission statement remains the same :

  “To create, as a community, the leading international open source digital analytics platform, that gives every user full control of their data.”

  Matomo provides a range of amazing and innovative features, allowing you to get a 360 view of your visitors. These insights are invaluable to help understand behavior, keep track of goals, and increase conversion rates and revenue.

  Who will deliver Matomo professional services ?

  Any company who wishes to. The only exception is that no companies will be allowed to have the name Matomo.

  Our company providing professional services is and will remain InnoCraft.

  Where can I follow the Matomo project ?

  Our new website will be matomo.org (automatically redirected from Piwik.org)

  Follow our new Twitter : twitter.com/matomo_org

  Github : github.com/matomo-org

  Facebook : facebook.com/Matomo.org

  Linkedin : linkedin.com/company/matomo/

  If you are already following us on social media, you will be kept up to date with Matomo automatically as all social media accounts will be redirected.

  How should I pronounce Matomo ?

  If you’re wondering how to say ‘Matomo’, you can find out by clicking play :

  Where can I see a demo of Matomo ?

  On demo.matomo.org

  Where can I download Matomo first release ?

  On matomo.org/download

  (Matomo 3.3.0 will be released in the next few days)

  What is the new logo ?

  Check it out below.

  

  Matomo trademark Policy

  Matomo is an internationally registered trademark of Matthieu Aubry, Founder of Piwik (now Matomo).

  Information about how to use the name Matomo (and logo) can be found here : matomo.org/trademark/

  What are the next big steps ?

  We will keep it simple for our valued users. As it is just a name change, the only thing you will notice is that the Piwik brand will gradually be replaced on the websites you are used to seeing the name on. The first version of Matomo will be available in just a few days for download. The software version numbers stay the same : the next release after Piwik 3.2.1 will be Matomo 3.3.0.

  All our public HTTP APIs and Tracking SDKs will continue working normally. As you can imagine, there is a lot of work and complexity behind slowly updating all the SDKs and keeping backwards compatibility, so our renaming project will take a few weeks to complete.

  The Matomo trademark will later be transferred into the Matomo foundation, a non-profit that will be dedicated to promoting and ensuring access to Matomo and our related open source projects in perpetuity.

  ---

  Thank you

  Thank you for continuing to support our project, alongside our 20+ Matomo core team members and more than 500 contributors.

  Please help to spread the word about this announcement by sharing it with friends or or colleagues who may benefit from using Matomo Analytics !

  The post Piwik is now Matomo – Announcement appeared first on Analytics Platform - Matomo.