From 0f9bfb784b7bbccf86b7d7d241982ba4e703efd4 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Sun, 25 Aug 2013 11:40:19 +0000
Subject: preliminary support for avconv/avprobe from libav

avconv is capable of outputting to the .sox format, greatly
simplifying our life as it enables us to easily apply sox
effects on a per-source file basis.

dtas-sourceedit and the "source" protocol commands will need
to change to support internal priorities (like sink).
---
 lib/dtas/source/av.rb | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 lib/dtas/source/av.rb

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

diff --git a/lib/dtas/source/av.rb b/lib/dtas/source/av.rb
new file mode 100644
index 0000000..804a66b
--- /dev/null
+++ b/lib/dtas/source/av.rb
@@ -0,0 +1,97 @@
+# -*- 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'
+
+# this is usually one input file
+class DTAS::Source::Av # :nodoc:
+  require_relative 'file'
+
+  include DTAS::Source::File
+
+  AV_DEFAULTS = COMMAND_DEFAULTS.merge(
+    "command" =>
+      'avconv -v error $SSPOS -i "$INFILE" -f sox - | sox -p $SOXFMT - $RGFX',
+    "comments" => nil,
+  )
+
+  attr_reader :precision # always 32
+  attr_reader :format
+
+  def self.try(infile, offset = nil)
+    err = ""
+    DTAS::Process.qx(%W(avprobe #{infile}), err: err)
+    return if err =~ /Unable to find a suitable output format for/
+    new(infile, offset)
+  rescue
+  end
+
+  def initialize(infile, offset = nil)
+    command_init(AV_DEFAULTS)
+    source_file_init(infile, offset)
+    @precision = 32 # this still goes through sox, which is 32-bit
+    do_avprobe
+  end
+
+  def do_avprobe
+    @duration = nil
+    @format = DTAS::Format.new
+    @format.bits = @precision
+    @comments = {}
+    err = ""
+    s = qx(%W(avprobe -show_streams -show_format #@infile), err: err)
+    s.scan(%r{^\[STREAM\]\n(.*?)\n\[/STREAM\]\n}m) do |_|
+      stream = $1
+      # XXX what to do about multiple streams?
+      if stream =~ /^codec_type=audio$/
+        duration = channels = rate = nil
+        stream =~ /^duration=([\d\.]+)\s*$/m and duration = $1.to_f
+        stream =~ /^channels=(\d)\s*$/m and channels = $1.to_i
+        stream =~ /^sample_rate=([\d\.]+)\s*$/m and rate = $1.to_i
+        if channels > 0 && rate > 0
+          @duration = duration
+          @format.channels = channels
+          @format.rate = rate
+        end
+      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
+  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 spawn(format, rg_state, opts)
+    raise "BUG: #{self.inspect}#spawn called twice" if @to_io
+    e = @format.to_env
+    e["INFILE"] = @infile
+
+    # make sure these are visible to the "current" command...
+    @env["SSPOS"] = @offset ? sspos(@offset) : nil
+    @env["RGFX"] = rg_state.effect(self) || nil
+    e.merge!(@rg.to_env) if @rg
+
+    @pid = dtas_spawn(e.merge!(@env), 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
+    to_hash.delete_if { |k,v| v == AV_DEFAULTS[k] }
+  end
+end
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