MP4 is an extensible container file, meaning that it does not define a strict structure and allows custom structure and hierarchy for each media type. The data in the MP4 file is divided into two sections, the first containing the media-related data and the second containing metadata. The media data contains audio or video and metadata indicate flags for random access, timestamps, etc. The structures in MP4 are typically referred to as atoms or boxes. The minimum size of an atom is 8 bytes(the first 4 bytes specify size and the next 4 bytes specify type). Here is a list of the root level atoms contained in MP files:
ftyp: Contains the file type, description, and the common data structures used.
pdin: Contains progressive video loading/downloading information.
moov: Container for all the movie metadata.
moof: Container with video fragments.
mfra: The container with random access to the video fragment
mdat: Data container for media.
stts: sample-to-time table.
stsc: sample-to-chunk table.
stsz: sample sizes (framing)
meta: The container with the metadata information.
General Complete name : C:\file_example_MP4_480_1_5MG.mp4 Format : MPEG-4 Format profile : Base Media / Version 2 Codec ID : mp42 (mp42/mp41/isom/avc1) File size : 1.50 MiB Duration : 30 s 527 ms Overall bit rate : 411 kb/s Encoded date : UTC 2015-08-07 09:13:02 Tagged date : UTC 2015-08-07 09:13:02
Video ID : 1 Format : AVC Format/Info : Advanced Video Codec Format profile : Baseline@L3 Format settings : 3 Ref Frames Format settings, CABAC : No Format settings, Reference fra : 3 frames Format settings, GOP : M=1, N=90 Codec ID : avc1 Codec ID/Info : Advanced Video Coding Duration : 30 s 33 ms Bit rate : 300 kb/s Width : 480 pixels Height : 270 pixels Display aspect ratio : 16:9 Frame rate mode : Constant Frame rate : 30.000 FPS Color space : YUV Chroma subsampling : 4:2:0 Bit depth : 8 bits Scan type : Progressive Bits/(Pixel*Frame) : 0.077 Stream size : 1.08 MiB (72%) Writing library : x264 core 146 r11M 121396c Encoding settings : cabac=0 / ref=3 / deblock=1:0:0 / analyse=0x1:0x111 / me=hex / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=48 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / stitchable=1 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=infinite / keyint_min=30 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=300 / ratetol=1.0 / qcomp=0.60 / qpmin=5 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=330 / vbv_bufsize=360 / nal_hrd=none / filler=0 / ip_ratio=1.40 / aq=1:1.00 Encoded date : UTC 2015-08-07 09:13:02 Tagged date : UTC 2015-08-07 09:13:02 Codec configuration box : avcC
Audio ID : 2 Format : AAC LC Format/Info : Advanced Audio Codec Low Complexity Codec ID : mp4a-40-2 Duration : 30 s 527 ms Bit rate mode : Constant Bit rate : 112 kb/s Channel(s) : 2 channels Channel layout : L R Sampling rate : 48.0 kHz Frame rate : 46.875 FPS (1024 SPF) Compression mode : Lossy Stream size : 417 KiB (27%) Encoded date : UTC 2015-08-07 09:13:02 Tagged date : UTC 2015-08-07 09:13:02
