<HTML><BODY><div>Hi.</div><div> </div><ol><li>Given some mp4 file, I need to retrive fragment from it. Say I’m interested of a fragment on k second of a video file, I need to retrieve video fragment from k-2 second to k+2 second, namely few seconds before interested event, few second after interested event. <span style="font-family: var(--vkui--octavius_font_family_global,var(--vkui--font_family_base,Helvetica,Arial,sans-serif)); letter-spacing: var(--vkui--font_text--letter_spacing--regular,normal);">What is the best approach (pipeline) </span><span style="font-family: var(--vkui--octavius_font_family_global,var(--vkui--font_family_base,Helvetica,Arial,sans-serif)); letter-spacing: var(--vkui--font_text--letter_spacing--regular,normal);">to do that?</span></li><li>What is the correct way to concatenate mp4 files, is it simple stream concatenation — append one file to another or there could be corner cases?</li></ol><div> </div><div>Thanks in advance.</div><div> </div></BODY></HTML>