C2SoftAvcEnc: Allocate output buffer as per clip's dimensions

Instead of allocating a fixed size output buffer, allocate it as per
width and height of the input being encoded. To ensure for very low
resolutions, this size doesn't become too small, use a minimum size of
512K Bytes.

Bug: 144928581
Test: h264 related tests in android.media.cts.VideoEncoderTest
Change-Id: I01c1aa03456043824354005f1708f07b3268d97e

media/codec2/components/avc/C2SoftAvcEnc.cpp

@@ -40,7 +40,7 @@ namespace android {
 namespace {
 
 constexpr char COMPONENT_NAME[] = "c2.android.avc.encoder";
-
+constexpr uint32_t kMinOutBufferSize = 524288;
 void ParseGop(
         const C2StreamGopTuning::output &gop,
         uint32_t *syncInterval, uint32_t *iInterval, uint32_t *maxBframes) {
@@ -440,8 +440,7 @@ C2SoftAvcEnc::C2SoftAvcEnc(
       mSignalledError(false),
       mCodecCtx(nullptr),
       mOutBlock(nullptr),
-      // TODO: output buffer size
-      mOutBufferSize(524288) {
+      mOutBufferSize(kMinOutBufferSize) {
 
     // If dump is enabled, then open create an empty file
     GENERATE_FILE_NAMES();
@@ -951,6 +950,9 @@ c2_status_t C2SoftAvcEnc::initEncoder() {
 
     mStride = width;
 
+    // Assume worst case output buffer size to be equal to number of bytes in input
+    mOutBufferSize = std::max(width * height * 3 / 2, kMinOutBufferSize);
+
     // TODO
     mIvVideoColorFormat = IV_YUV_420P;