RentACodec: New class that takes over part of ACMCodecDB's job

webrtc/modules/audio_coding/main/acm2/rent_a_codec.h

Index: webrtc/modules/audio_coding/main/acm2/rent_a_codec.h
diff --git a/webrtc/modules/audio_coding/main/acm2/rent_a_codec.h b/webrtc/modules/audio_coding/main/acm2/rent_a_codec.h
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index 0000000000000000000000000000000000000000..cfbb4ce0a55505af9e1fe134bfad6df468f44ac1
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+++ b/webrtc/modules/audio_coding/main/acm2/rent_a_codec.h
@@ -0,0 +1,127 @@
+/*
+ *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_CODING_MAIN_ACM2_RENT_A_CODEC_H_
+#define WEBRTC_MODULES_AUDIO_CODING_MAIN_ACM2_RENT_A_CODEC_H_
+
+#include <stddef.h>
+
+#include "webrtc/base/array_view.h"
+#include "webrtc/base/maybe.h"
+#include "webrtc/typedefs.h"
+
+namespace webrtc {
+
+struct CodecInst;
+
+namespace acm2 {
+
+class RentACodec {
+ public:
+  enum class CodecId {
+#if defined(WEBRTC_CODEC_ISAC) || defined(WEBRTC_CODEC_ISACFX)
+    kISAC,
+#endif
+#ifdef WEBRTC_CODEC_ISAC
+    kISACSWB,
+#endif
+    // Mono
+    kPCM16B,
+    kPCM16Bwb,
+    kPCM16Bswb32kHz,
+    // Stereo
+    kPCM16B_2ch,
+    kPCM16Bwb_2ch,
+    kPCM16Bswb32kHz_2ch,
+    // Mono
+    kPCMU,
+    kPCMA,
+    // Stereo
+    kPCMU_2ch,
+    kPCMA_2ch,
+#ifdef WEBRTC_CODEC_ILBC
+    kILBC,
+#endif
+#ifdef WEBRTC_CODEC_G722
+    kG722,      // Mono
+    kG722_2ch,  // Stereo
+#endif
+#ifdef WEBRTC_CODEC_OPUS
+    kOpus,  // Mono and stereo
+#endif
+    kCNNB,
+    kCNWB,
+    kCNSWB,
+#ifdef ENABLE_48000_HZ
+    kCNFB,
+#endif
+    kAVT,
+#ifdef WEBRTC_CODEC_RED
+    kRED,
+#endif
+    kNumCodecs,  // Implementation detail. Don't use.
+
+// Set unsupported codecs to -1.
+#if !defined(WEBRTC_CODEC_ISAC) && !defined(WEBRTC_CODEC_ISACFX)
+    kISAC = -1,
+#endif
+#ifndef WEBRTC_CODEC_ISAC
+    kISACSWB = -1,
+#endif
+    // 48 kHz not supported, always set to -1.
+    kPCM16Bswb48kHz = -1,
+#ifndef WEBRTC_CODEC_ILBC
+    kILBC = -1,
+#endif
+#ifndef WEBRTC_CODEC_G722
+    kG722 = -1,      // Mono
+    kG722_2ch = -1,  // Stereo
+#endif
+#ifndef WEBRTC_CODEC_OPUS
+    kOpus = -1,  // Mono and stereo
+#endif
+#ifndef WEBRTC_CODEC_RED
+    kRED = -1,
+#endif
+#ifndef ENABLE_48000_HZ
+    kCNFB = -1,
+#endif
+
+    kNone = -1
+  };
+
+  static inline size_t NumberOfCodecs() {
+    return static_cast<size_t>(CodecId::kNumCodecs);
+  }
+  static inline rtc::Maybe<int> CodecIndexFromId(CodecId codec_id) {

[hlundin-webrtc, 2015/10/27 13:52:02]

I wouldn't mind an empty line between each method here.

[kwiberg-webrtc, 2015/10/27 14:43:23]

Done.

+    const int i = static_cast<int>(codec_id);
+    return i < static_cast<int>(NumberOfCodecs()) ? i : rtc::Maybe<int>();
+  }
+  static inline rtc::Maybe<CodecId> CodecIdFromIndex(int codec_index) {
+    return static_cast<size_t>(codec_index) < NumberOfCodecs()
+               ? static_cast<RentACodec::CodecId>(codec_index)
+               : rtc::Maybe<RentACodec::CodecId>();
+  }
+  static rtc::Maybe<CodecId> CodecIdByParams(const char* payload_name,
+                                             int sampling_freq_hz,
+                                             int channels);
+  static rtc::Maybe<CodecInst> CodecInstById(CodecId codec_id);
+  static rtc::Maybe<CodecInst> CodecInstByParams(const char* payload_name,

[the sun, 2015/10/27 14:07:07]

Sorry for the naïve question, but... Isn't this the only function needed (pretty
much)? When do we actually want to use the above list of CodecId:s?

[kwiberg-webrtc, 2015/10/27 14:43:23]

They're all needed at the moment, because old callers that I haven't changed.
The plan is that the Rent-A-Codec will swallow the codec creation code that
calls all of these, at which point they'll disappear inside its event horizon,
so that no one outside the Rent-A-Codec will see them. Further
Rent-A-Codec-internal refactoring can then take place.

+                                                 int sampling_freq_hz,
+                                                 int channels);
+  static bool IsCodecValid(const CodecInst& codec_inst);
+
+  static rtc::ArrayView<const CodecInst> Database();
+};
+
+}  // namespace acm2
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_CODING_MAIN_ACM2_RENT_A_CODEC_H_