feat(core): made AVCCBufferWriter support AVCC frame

core/src/main/java/io/github/thibaultbee/streampack/internal/utils/av/buffer/ByteBufferWriter.kt

@@ -15,6 +15,8 @@
  */
 package io.github.thibaultbee.streampack.internal.utils.av.buffer
 
+import io.github.thibaultbee.streampack.internal.utils.extensions.isAnnexB
+import io.github.thibaultbee.streampack.internal.utils.extensions.isAvcc
 import io.github.thibaultbee.streampack.internal.utils.extensions.removeStartCode
 import io.github.thibaultbee.streampack.internal.utils.extensions.startCodeSize
 import java.nio.ByteBuffer
@@ -51,12 +53,31 @@ class PassthroughBufferWriter(private val buffer: ByteBuffer) : ByteBufferWriter
  * A class that convert a [ByteBuffer] to an AVCC format.
  */
 class AVCCBufferWriter(private val buffer: ByteBuffer) : ByteBufferWriter() {
-    override val size = buffer.remaining() - buffer.startCodeSize + 4
+    override val size = computeSize()
+
+    private val isAvcc = buffer.isAvcc
+    private val isAnnexB = buffer.isAnnexB
+
+    private fun computeSize(): Int {
+        return if (isAvcc) {
+            buffer.remaining()
+        } else if (isAnnexB) {
+            buffer.remaining() - buffer.startCodeSize + 4
+        } else {
+            throw IllegalArgumentException("Buffer must be in AVCC or AnnexB format")
+        }
+    }
 
     override fun write(output: ByteBuffer) {
-        val noStartCodeBuffer = buffer.removeStartCode()
-        output.putInt(noStartCodeBuffer.remaining())
-        output.put(noStartCodeBuffer)
+        if (isAvcc) {
+            output.put(buffer)
+        } else if (isAnnexB) {
+            val noStartCodeBuffer = buffer.removeStartCode()
+            output.putInt(noStartCodeBuffer.remaining())
+            output.put(noStartCodeBuffer)
+        } else {
+            throw IllegalArgumentException("Buffer must be in AVCC or AnnexB format")
+        }
     }
 }