UniquePtr: Support SrsUniquePtr to replace SrsAutoFree. v6.0.136 (#4109)

To manage an object:

```cpp
// Before
MyClass* ptr = new MyClass();
SrsAutoFree(MyClass, ptr);
ptr->do_something();

// Now
SrsUniquePtr<MyClass> ptr(new MyClass());
ptr->do_something();
```

To manage an array of objects:

```cpp
// Before
char* ptr = new char[10];
SrsAutoFreeA(char, ptr);
ptr[0] = 0xf;

// Now
SrsUniquePtr<char[]> ptr(new char[10]);
ptr[0] = 0xf;
```

In fact, SrsUniquePtr is a limited subset of SrsAutoFree, mainly
managing pointers and arrays. SrsUniquePtr is better than SrsAutoFree
because it has the same API to standard unique ptr.

```cpp
SrsUniquePtr<MyClass> ptr(new MyClass());
ptr->do_something();
MyClass* p = ptr.get();
```

SrsAutoFree actually uses a pointer to a pointer, so it can be set to
NULL, allowing the pointer's value to be changed later (this usage is
different from SrsUniquePtr).

```cpp
// OK to free ptr correctly.
MyClass* ptr;
SrsAutoFree(MyClass, ptr);
ptr = new MyClass();

// Crash because ptr is an invalid pointer.
MyClass* ptr;
SrsUniquePtr<MyClass> ptr(ptr);
ptr = new MyClass();
```

Additionally, SrsAutoFreeH can use specific release functions, which
SrsUniquePtr does not support.

---------

Co-authored-by: Jacob Su <suzp1984@gmail.com>

trunk/src/kernel/srs_kernel_codec.cpp

@@ -730,13 +730,12 @@ srs_error_t SrsVideoFrame::parse_avc_b_frame(const SrsSample* sample, bool& is_b
         return err;
     }
 
-    SrsBuffer* stream = new SrsBuffer(sample->bytes, sample->size);
-    SrsAutoFree(SrsBuffer, stream);
+    SrsUniquePtr<SrsBuffer> stream(new SrsBuffer(sample->bytes, sample->size));
 
     // Skip nalu header.
     stream->skip(1);
 
-    SrsBitBuffer bitstream(stream);
+    SrsBitBuffer bitstream(stream.get());
     int32_t first_mb_in_slice = 0;
     if ((err = srs_avc_nalu_read_uev(&bitstream, first_mb_in_slice)) != srs_success) {
         return srs_error_wrap(err, "nalu read uev");
@@ -793,10 +792,9 @@ srs_error_t SrsFormat::on_audio(int64_t timestamp, char* data, int size)
         srs_info("no audio present, ignore it.");
         return err;
     }
-    
-    SrsBuffer* buffer = new SrsBuffer(data, size);
-    SrsAutoFree(SrsBuffer, buffer);
-    
+
+    SrsUniquePtr<SrsBuffer> buffer(new SrsBuffer(data, size));
+
     // We already checked the size is positive and data is not NULL.
     srs_assert(buffer->require(1));
     
@@ -824,10 +822,10 @@ srs_error_t SrsFormat::on_audio(int64_t timestamp, char* data, int size)
     buffer->skip(-1 * buffer->pos());
     
     if (codec == SrsAudioCodecIdMP3) {
-        return audio_mp3_demux(buffer, timestamp, fresh);
+        return audio_mp3_demux(buffer.get(), timestamp, fresh);
     }
     
-    return audio_aac_demux(buffer, timestamp);
+    return audio_aac_demux(buffer.get(), timestamp);
 }
 
 srs_error_t SrsFormat::on_video(int64_t timestamp, char* data, int size)
@@ -838,11 +836,9 @@ srs_error_t SrsFormat::on_video(int64_t timestamp, char* data, int size)
         srs_trace("no video present, ignore it.");
         return err;
     }
-    
-    SrsBuffer* buffer = new SrsBuffer(data, size);
-    SrsAutoFree(SrsBuffer, buffer);
 
-    return video_avc_demux(buffer, timestamp);
+    SrsUniquePtr<SrsBuffer> buffer(new SrsBuffer(data, size));
+    return video_avc_demux(buffer.get(), timestamp);
 }
 
 srs_error_t SrsFormat::on_aac_sequence_header(char* data, int size)
@@ -2807,10 +2803,9 @@ srs_error_t SrsFormat::audio_mp3_demux(SrsBuffer* stream, int64_t timestamp, boo
 srs_error_t SrsFormat::audio_aac_sequence_header_demux(char* data, int size)
 {
     srs_error_t err = srs_success;
-    
-    SrsBuffer* buffer = new SrsBuffer(data, size);
-    SrsAutoFree(SrsBuffer, buffer);
-    
+
+    SrsUniquePtr<SrsBuffer> buffer(new SrsBuffer(data, size));
+
     // only need to decode the first 2bytes:
     //      audioObjectType, aac_profile, 5bits.
     //      samplingFrequencyIndex, aac_sample_rate, 4bits.