From bc00dd1b3fee22bd91bd713e697b8b31be978d4e Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Mon, 26 Aug 2013 08:26:58 +0000
Subject: add lightly-tested ffmpeg support

Since ffmpeg/ffprobe are wrappers around their libav-variants,
I haven't had the chance to actually test with "real" ffmpeg,
but the usage is probably similar enough to not matter.
---
 lib/dtas/source/av_ff_common.rb | 123 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 lib/dtas/source/av_ff_common.rb

(limited to 'lib/dtas/source/av_ff_common.rb')

diff --git a/lib/dtas/source/av_ff_common.rb b/lib/dtas/source/av_ff_common.rb
new file mode 100644
index 0000000..08f5b0c
--- /dev/null
+++ b/lib/dtas/source/av_ff_common.rb
@@ -0,0 +1,123 @@
+# -*- encoding: binary -*-
+# Copyright (C) 2013, Eric Wong <normalperson@yhbt.net>
+# License: GPLv3 or later (https://www.gnu.org/licenses/gpl-3.0.txt)
+require_relative '../../dtas'
+require_relative '../source'
+require_relative '../replaygain'
+require_relative 'file'
+
+module DTAS::Source::AvFfCommon
+  include DTAS::Source::File
+  AStream = Struct.new(:duration, :channels, :rate)
+  AV_FF_TRYORDER = 1
+
+  attr_reader :precision # always 32
+  attr_reader :format
+
+  def try(infile, offset = nil)
+    rv = source_file_dup(infile, offset)
+    rv.av_ff_ok? or return
+    rv
+  end
+
+  def av_ff_ok?
+    @duration = nil
+    @format = DTAS::Format.new
+    @format.bits = 32 # always, since we still use the "sox" format
+    @comments = {}
+    @astreams = []
+    cmd = %W(#@av_ff_probe -show_streams -show_format #@infile)
+    err = ""
+    s = qx(@env, cmd, err_str: err, no_raise: true)
+    return false if Process::Status === s
+    return false if err =~ /Unable to find a suitable output format for/
+    s.scan(%r{^\[STREAM\]\n(.*?)\n\[/STREAM\]\n}m) do |_|
+      stream = $1
+      if stream =~ /^codec_type=audio$/
+        as = AStream.new
+        index = nil
+        stream =~ /^index=(\d+)\s*$/m and index = $1.to_i
+        stream =~ /^duration=([\d\.]+)\s*$/m and as.duration = $1.to_f
+        stream =~ /^channels=(\d)\s*$/m and as.channels = $1.to_i
+        stream =~ /^sample_rate=([\d\.]+)\s*$/m and as.rate = $1.to_i
+        index or raise "BUG: no audio index from #{Shellwords.join(cmd)}"
+
+        # some streams have zero channels
+        @astreams[index] = as if as.channels > 0 && as.rate > 0
+      end
+    end
+    s.scan(%r{^\[FORMAT\]\n(.*?)\n\[/FORMAT\]\n}m) do |_|
+      f = $1
+      f =~ /^duration=([\d\.]+)\s*$/m and @duration = $1.to_f
+      # TODO: multi-line/multi-value/repeated tags
+      f.gsub!(/^TAG:([^=]+)=(.*)$/i) { |_| @comments[$1.upcase] = $2 }
+    end
+    ! @astreams.empty?
+  end
+
+  def sspos(offset)
+    offset =~ /\A(\d+)s\z/ or return "-ss #{offset}"
+    samples = $1.to_f
+    sprintf("-ss %0.9g", samples / @format.rate)
+  end
+
+  def select_astream(as)
+    @format.channels = as.channels
+    @format.rate = as.rate
+
+    # favor the duration of the stream we're playing instead of
+    # duration we got from [FORMAT].  However, some streams may not have
+    # a duration and only have it in [FORMAT]
+    @duration = as.duration if as.duration
+  end
+
+  def amap_fallback
+    @astreams.each_with_index do |as, index|
+      as or next
+      select_astream(as)
+      warn "no suitable audio stream in #@infile, trying stream=#{index}"
+      return "-map 0:#{i}"
+    end
+    raise "BUG: no audio stream in #@infile"
+  end
+
+  def spawn(player_format, rg_state, opts)
+    raise "BUG: #{self.inspect}#spawn called twice" if @to_io
+    amap = nil
+
+    # try to find an audio stream which matches our channel count
+    # we need to set @format for sspos() down below
+    @astreams.each_with_index do |as, i|
+      if as && as.channels == player_format.channels
+        select_astream(as)
+        amap = "-map 0:#{i}"
+      end
+    end
+
+    # fall back to the first audio stream
+    # we must call select_astream before sspos
+    amap ||= amap_fallback
+
+    e = @env.merge!(player_format.to_env)
+
+    # make sure these are visible to the source command...
+    e["INFILE"] = @infile
+    e["AMAP"] = amap
+    e["SSPOS"] = @offset ? sspos(@offset) : nil
+    e["RGFX"] = rg_state.effect(self) || nil
+    e.merge!(@rg.to_env) if @rg
+
+    @pid = dtas_spawn(e, command_string, opts)
+  end
+
+  # This is the number of samples according to the samples in the source
+  # file itself, not the decoded output
+  def samples
+    @samples ||= (@duration * @format.rate).round
+  end
+
+  def to_hsh
+    sd = source_defaults
+    to_hash.delete_if { |k,v| v == sd[k] }
+  end
+end
-- 
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