forked from AkkomaGang/akkoma
c4439c630f
grep -rl '# Copyright © .* Pleroma' * | xargs sed -i 's;Copyright © .* Pleroma .*;Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>;'
131 lines
3.8 KiB
Elixir
131 lines
3.8 KiB
Elixir
# Pleroma: A lightweight social networking server
|
|
# Copyright © 2017-2021 Pleroma Authors <https://pleroma.social/>
|
|
# SPDX-License-Identifier: AGPL-3.0-only
|
|
|
|
defmodule Pleroma.Helpers.QtFastStart do
|
|
@moduledoc """
|
|
(WIP) Converts a "slow start" (data before metadatas) mov/mp4 file to a "fast start" one (metadatas before data).
|
|
"""
|
|
|
|
# TODO: Cleanup and optimizations
|
|
# Inspirations: https://www.ffmpeg.org/doxygen/3.4/qt-faststart_8c_source.html
|
|
# https://github.com/danielgtaylor/qtfaststart/blob/master/qtfaststart/processor.py
|
|
# ISO/IEC 14496-12:2015, ISO/IEC 15444-12:2015
|
|
# Paracetamol
|
|
|
|
def fix(<<0x00, 0x00, 0x00, _, 0x66, 0x74, 0x79, 0x70, _::bits>> = binary) do
|
|
index = fix(binary, 0, nil, nil, [])
|
|
|
|
case index do
|
|
:abort -> binary
|
|
[{"ftyp", _, _, _, _}, {"mdat", _, _, _, _} | _] -> faststart(index)
|
|
[{"ftyp", _, _, _, _}, {"free", _, _, _, _}, {"mdat", _, _, _, _} | _] -> faststart(index)
|
|
_ -> binary
|
|
end
|
|
end
|
|
|
|
def fix(binary) do
|
|
binary
|
|
end
|
|
|
|
# MOOV have been seen before MDAT- abort
|
|
defp fix(<<_::bits>>, _, true, false, _) do
|
|
:abort
|
|
end
|
|
|
|
defp fix(
|
|
<<size::integer-big-size(32), fourcc::bits-size(32), rest::bits>>,
|
|
pos,
|
|
got_moov,
|
|
got_mdat,
|
|
acc
|
|
) do
|
|
full_size = (size - 8) * 8
|
|
<<data::bits-size(full_size), rest::bits>> = rest
|
|
|
|
acc = [
|
|
{fourcc, pos, pos + size, size,
|
|
<<size::integer-big-size(32), fourcc::bits-size(32), data::bits>>}
|
|
| acc
|
|
]
|
|
|
|
fix(rest, pos + size, got_moov || fourcc == "moov", got_mdat || fourcc == "mdat", acc)
|
|
end
|
|
|
|
defp fix(<<>>, _pos, _, _, acc) do
|
|
:lists.reverse(acc)
|
|
end
|
|
|
|
defp faststart(index) do
|
|
{{_ftyp, _, _, _, ftyp}, index} = List.keytake(index, "ftyp", 0)
|
|
|
|
# Skip re-writing the free fourcc as it's kind of useless.
|
|
# Why stream useless bytes when you can do without?
|
|
{free_size, index} =
|
|
case List.keytake(index, "free", 0) do
|
|
{{_, _, _, size, _}, index} -> {size, index}
|
|
_ -> {0, index}
|
|
end
|
|
|
|
{{_moov, _, _, moov_size, moov}, index} = List.keytake(index, "moov", 0)
|
|
offset = -free_size + moov_size
|
|
rest = for {_, _, _, _, data} <- index, do: data, into: []
|
|
<<moov_head::bits-size(64), moov_data::bits>> = moov
|
|
[ftyp, moov_head, fix_moov(moov_data, offset, []), rest]
|
|
end
|
|
|
|
defp fix_moov(
|
|
<<size::integer-big-size(32), fourcc::bits-size(32), rest::bits>>,
|
|
offset,
|
|
acc
|
|
) do
|
|
full_size = (size - 8) * 8
|
|
<<data::bits-size(full_size), rest::bits>> = rest
|
|
|
|
data =
|
|
cond do
|
|
fourcc in ["trak", "mdia", "minf", "stbl"] ->
|
|
# Theses contains sto or co64 part
|
|
[<<size::integer-big-size(32), fourcc::bits-size(32)>>, fix_moov(data, offset, [])]
|
|
|
|
fourcc in ["stco", "co64"] ->
|
|
# fix the damn thing
|
|
<<version::integer-big-size(32), count::integer-big-size(32), rest::bits>> = data
|
|
|
|
entry_size =
|
|
case fourcc do
|
|
"stco" -> 32
|
|
"co64" -> 64
|
|
end
|
|
|
|
[
|
|
<<size::integer-big-size(32), fourcc::bits-size(32), version::integer-big-size(32),
|
|
count::integer-big-size(32)>>,
|
|
rewrite_entries(entry_size, offset, rest, [])
|
|
]
|
|
|
|
true ->
|
|
[<<size::integer-big-size(32), fourcc::bits-size(32)>>, data]
|
|
end
|
|
|
|
acc = [acc | data]
|
|
fix_moov(rest, offset, acc)
|
|
end
|
|
|
|
defp fix_moov(<<>>, _, acc), do: acc
|
|
|
|
for size <- [32, 64] do
|
|
defp rewrite_entries(
|
|
unquote(size),
|
|
offset,
|
|
<<pos::integer-big-size(unquote(size)), rest::bits>>,
|
|
acc
|
|
) do
|
|
rewrite_entries(unquote(size), offset, rest, [
|
|
acc | <<pos + offset::integer-big-size(unquote(size))>>
|
|
])
|
|
end
|
|
end
|
|
|
|
defp rewrite_entries(_, _, <<>>, acc), do: acc
|
|
end
|