On 4/9/16, Carl Eugen Hoyos <[email protected]> wrote: > Sreenath BH <bhsreenath@...> writes: > >> 4. container format is MP4 > > Please elaborate a little: > How do you generally identify an mp4 file (without using FFmpeg)? > >> "mov,mp4,m4a,3gp,3g2,mj2" > > From FFmpeg pov, this string identifies a specific container format. > > Carl Eugen > > _______________________________________________ > Libav-user mailing list > [email protected] > http://ffmpeg.org/mailman/listinfo/libav-user >
Hi Carl to answer your question: I don't know any other way to identify an MP4 file other than using ffmpeg lbraries/command. I have just started to look at the file structure of video files, and see that the first few bytes of video files have 'fields' that indicate the container type. If I use hexdump -C on video files, I see the following: on a mp4 file: 00000000 00 00 00 18 66 74 79 70 6d 70 34 32 00 00 00 00 |....ftypmp42....| 00000010 69 73 6f 6d 6d 70 34 32 00 02 62 25 6d 6f 6f 76 |isommp42..b%moov| on one sample 3gp file: 00000000 00 00 00 1c 66 74 79 70 33 67 70 34 00 00 02 00 |....ftyp3gp4....| 00000010 69 73 6f 6d 69 73 6f 32 33 67 70 34 00 00 00 08 |isomiso23gp4....| So I guess if I have two video files, one mp4 and the other 3gp, but both using H264 and AAC codecs, I can use the above data to identify them. I was assuming/hoping that libav would be able to provide this information since it anyway opens the file and reads all information available. So my question now is, is opening the file and reading first few bytes (around 20 or so) and checking them the way to go? thanks, Sreenath _______________________________________________ Libav-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/libav-user
