z8
101 lines
2.6 KiB
Markdown
101 lines
2.6 KiB
Markdown
# MP4 muxer
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## Info
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This code is only meant to work with ALAC and EAC3 (JOC) streams, for any other codecs you're on your own.
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Use at your own risk. If you use this to create files and don't validate them afterwards, don't blame me if something goes wrong.
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None of this code will parse MP4 files for you. If your source file is a different MP4 file (or a different format entirely),
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you will have to figure out how to parse the required information (see `Usage`) yourself.
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For more information, see [here](https://z8.re/blog/mp4).
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## Usage
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You will need to provide the following info:
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- Sample rate
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- Bit depth
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- mdat box as a bytearray
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- Sizes for all samples contained within the mdat box
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- Total duration
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- (optional: Tags)
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Writing tags is optional, even without them the file will play back just fine. They're written to `moov/udta/meta/ilst`.
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If you do not create a `Tags` object and/or do not use `set_tags()`, then the `udta` box will not be created.
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Note for EAC3 JOC: This code assumes that there is only a single independed substream present and that the
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values in the EAC3 specific box within `stsd` of the source file match the following (I left out the reserved bits here):
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```python
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fscod = 0
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bsid = 16
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asvc = 0
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bsmod = 0
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acmod = 7
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lfeon = 1
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num_dep_sub = 0
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ec3_job_flag = 1
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joc_complexity_index = 16
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```
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## Example
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```python
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from mp4muxer_alac import MP4MuxerALAC
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m = MP4MuxerALAC()
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m.set_sample_rate(44100)
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m.set_bit_depth(16)
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sample_sizes = [7424, 6915, 6830, 6737, ..., 2700, 1443]
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m.set_sample_sizes(sample_sizes)
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m.set_total_duration(10442880)
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with open("m.dat", "rb") as f:
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mdat = bytearray(f.read())
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m.set_mdat_data(mdat)
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t = Tags()
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t.track_name = "Insert Interesting Title Here"
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t.artist = "Artist X & Y"
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t.album_artist = "Artist X"
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t.composer = "X, Y, Z"
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t.album_name = "First Track - Single"
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t.genre = "Dubstep;Country"
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t.track_number = 1
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t.total_number_of_tracks = 1
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t.disc_number = 1
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t.total_number_of_discs = 1
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t.date = "2020-05-22"
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t.upc = "5556667778889"
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t.label = "We Sell Records Rec."
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with open("cover.jpg", "rb") as f:
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t.cover_data = bytearray(f.read())
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t.cover_format = "jpeg"
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t.isrc = "CYZXL20044078"
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t.copyright = "℗ 2021 We Sell Records Rec."
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t.apple_store_catalog_id = 9999998
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t.album_title_id = 9999999
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t.playlist_id = 32423444
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m.set_tags(t)
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m.create()
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m.out("A Piece of Music.m4a")
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```
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For EAC3 JOC the process is similar:
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```python
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from mp4muxer_eac3 import MP4MuxerEAC3
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m = MP4MuxerEAC3()
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m.set_sample_rate(sr)
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m.set_bit_depth(bd)
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m.set_bit_rate(768)
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m.set_sample_sizes(sample_sizes)
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m.set_timestamp(timestamp)
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m.set_mdat_data(mdat)
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...
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```
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