Papers & articles

This is the page for papers and publications that i have made.

• Transitioning Broadcast to Cloud06/01/2021
  Abstract We analyze the differences between on-premise broadcast and cloud-based online video delivery workflows and identify technologies needed for bridging the gaps between them. Specifically, we note differences in ingest protocols, media formats, signal-processing chains, codec constraints, metadata, transport formats, delays, and means for implementing operations such as ad-splicing, redundancy and synchronization. To bridge theContinue reading “Transitioning Broadcast to Cloud”
• How we scale Live streaming for millions of viewers simultaneously22/10/2020
  Abstract As Facebook Live and Facebook Watch have grown, the content shared there has expanded to include professionally produced, broadcast-quality content, like shows and live event coverage. This type of professional broadcasting from providers like La Liga, CONMEBOL, and UEFA is a very different challenge from user generated content (UGC) and viewers’ expectations are much higher. ViewersContinue reading “How we scale Live streaming for millions of viewers simultaneously”
• Super fast HLS trimming with frame accuracy12/06/2016
  Description This article is an evolution of this code: Trim HLS stream with frame accuracy using ffmpeg and Bash script The implementation gets a group if HLS chunks (.ts) and based on input and output points (timestamps) it creates an mp4 output file frame accuracy trimmed, and with AV perfectly aligned. Thanks to the underlying algorithmContinue reading “Super fast HLS trimming with frame accuracy”
• A minimal h264 “encoder” (C++)31/08/2014
  Introduction I always thought that the best approach to complex things is to start from the basis, and once you control this part enter step by step towards more complex parts. With this idea in mind and the aim to improve my understanding of h264 bitstream and its techniques I have created the following code in C++ that generates a compliant h264 file fromContinue reading “A minimal h264 “encoder” (C++)”
• The audio video alignment nightmare in audio compressed formats08/08/2014
  Introduction Doing some research about automatic editing systems I have found strange timing behaviors in audio compressed streams and I wanted to take some measures, and here they are: Audio tests – Audacity Using Audacity  2.0.5 (free audio editor) I generated a test time line, see figure 1 After that I have exported the test timelineContinue reading “The audio video alignment nightmare in audio compressed formats”
• Trim HLS stream with frame accuracy using ffmpeg and Bash script07/08/2014
  Introduction The main idea of this post is to practise with ffmpeg and write down my experiences, issues that I have found, possible solutions, etc. To achieve that I developed a group of bash scripts that are able to trim a HLS stream using ffmpeg . The purpose of these scripts is to perform a VERY FASTContinue reading “Trim HLS stream with frame accuracy using ffmpeg and Bash script”
• JOCHLSDownloader (Ruby gem)27/07/2014
  The JOCHLSDownloader ruby gem is a very simple native ruby code that downloads all files linked by a m3u8 manifest (used in HLS), I have used several times for test purposes.   You can download the JOCHLSDownloader (Ruby version) from: Note: For LIVE and EVENT playlist types it downloads only the firsts media segments. For VOD playlistContinue reading “JOCHLSDownloader (Ruby gem)”
• Loudness meters [CAT]15/06/2014
  These slides are part of a conference that we gave about loudness (link). Different views of loudness were explained in that conference: Introduction by Llorenç Gómez (TVC) Standards by Josep Ramon Casas (UPC) Loudness meters by Jordi Cenzano (8TV) Loudness in production chain by Emili Planas (Mediapro) The conference was organized by Consell del AudiovisualContinue reading “Loudness meters [CAT]”
• Design and implementation of a loudness monitoring system – MERIT master thesis10/07/2013
  This paper was created in 07/2013 as MERIT master thesis (from UPC university). The main objective is to explore the normalization of audio levels in the media industry, which is a relevant issue nowadays. Many broadcast organizations around the world are concerned about this problem and they have published many papers and standards that are analyzed in this project, some of thoseContinue reading “Design and implementation of a loudness monitoring system – MERIT master thesis”
• Shape from silhouette and camera model slides01/12/2008
  This slides explains how to calculate the camera intrinsics matrix, camera extrinsics matrix, and camera projection matrix from camera model. And you can find an introduction of SFS (Shape From Silhouette) method.
• Object labeling in a multicamera environtment01/12/2008
  In this paper I describe an algorithm that it can relate objects from different images of the same scene. This algorithm needs like starting point the mask images from N full calibrated cameras. The algorithm is able to identify different objects presents in the scene and it can correlate these objects from one picture toContinue reading “Object labeling in a multicamera environtment”
• Multiview depth video coding using 3D Wavelets01/06/2008
  This work was done under 3D video coding subject of Merit Master (UPC). It evaluates the use of 3D wavelet  scheme to codify depth video images.
• RTP Protocol01/05/2008
  It describes the RTP protocol, and it proposes a C code to implement it and test it.
• Comparative of different block search methods in the block matching algorithm01/04/2006
  This work was done under Coding and Transmission of Multimedia Contents subject of Merit Master (UPC). This work is a comparison of different techniques of block matching algorithm (BM), the BM  algorithm is commonly used in image coding. In this work I implemented the BM algorithm using Matlab, and I evaluate it using different search methods.
• Compresión sin pérdidas de imágenes biomédicas o multiespectrales con Wavelets [ES]01/04/2006
  This work was done with Ferran Valldosera under Wavelets subject of Merit Master (UPC). It evaluates the use of Wavelets to codify a sequence of images (biomedical o multispectral).
• Adquisició de vídeo multicàmera per a una smartroom [CAT]01/09/2005
  This paper is my final grade thesis. It’s about to design and implement a cheap system of frame synchronized calibrated multicamera acquisition. The project includes to design all environment with limited budged, buy materials, implement customized software, write the documentation, and finally the test and debugging phase. This system was built in the smartroom of D5 module of UPCContinue reading “Adquisició de vídeo multicàmera per a una smartroom [CAT]”
• La compresión JPEG [ES]01/09/2001
  This is an aticle published in Antena magazine (official magazine of Spanish telecommunications college) on september of 2001. It explains all aspects of JPEG compression, from mathematical approach to a practical matlab implementation.