Some Random Stuff

In one of the blog posts we learned how to decode jpeg images using libavcodec. This is the second part of that post. In this we will learn how to encode decoded images (raw images) to theora and write them in ogg video file. In the end of the first part we saved our raw image in raw_data variable and its length in raw_data_size variable. Lets assume that we packaged all our decoding code in one function called "decode_jpeg_image" which has following signature int decode_jpeg_image(char *filename,int file_name_size,uint8_t *raw_data,int *raw_data_size) filename = name of jpeg file to decode file_name_size = length of jpeg file's name raw_data = contains decoded raw image on return raw_data_size = contains length of raw_data on return Now let's start working on how to encode this image in raw_data to theora and write that image to ogg video file. Finding Theora encoder We first have to find encoder for THEORA which is represented by AVCodec structure. He...

I got a chance to work on a video encoding application that decodes series of jpeg files and convert them into ogg theora video file. I used the infamous libavcodec library that is used in FFMPEG . I decided to write blog posts explaining how I decode jpeg images and convert them into ogg video file. This is the first part and in this I will explain how to decode jpeg images using libavcodec. To learn how to write decoded images as a ogg video file please read http://random-stuff-mine.blogspot.com/2017/07/encoding-raw-images-to-ogg-theora-video.html Before reading this blog post you must be aware of using and setting up libavcodec. I highly recommend this tutorial to get basics of using libavcodec http://www.ffmpeg.org/doxygen/0.6/api-example_8c-source.html Allocating input format context We will first allocate input format for reading the file. We will use avformat_open_input function that will allocate AVFormatContext structure passed to it , the function detects input typ...