Automatic Generation of H.264 Parameter Sets to Recover Video File Fragments (2104.14522v3)

Abstract: We address the problem of decoding video file fragments when the necessary encoding parameters are missing. With this objective, we propose a method that automatically generates H.264 video headers containing these parameters and extracts coded pictures in the partially available compressed video data. To accomplish this, we examined a very large corpus of videos to learn patterns of encoding settings commonly used by encoders and created a parameter dictionary. Further, to facilitate a more efficient search our method identifies characteristics of a coded bitstream to discriminate the entropy coding mode. It also utilizes the application logs created by the decoder to identify correct parameter values. Evaluation of the effectiveness of the proposed method on more than 55K videos with diverse provenance shows that it can generate valid headers on average in 11.3 decoding trials per video. This result represents an improvement by more than a factor of 10 over the conventional approach of video header stitching to recover video file fragments.