WIP fix decoding for the multiple frames per packet

Fix #174

Author: h4tr3d

src/avcpp/codeccontext.cpp

@@ -893,17 +893,28 @@ std::pair<int, const error_category *> CodecContext2::decodeCommon(AVFrame *outF
     if (!decodeProc)
         return make_error_pair(Errors::CodecInvalidDecodeProc);
 
-    if (offset && inPacket.size() && offset >= inPacket.size())
-        return make_error_pair(Errors::CodecDecodingOffsetToLarge);
-
+    // sizeof(AVPacket) is not a part of the public API
+    std::unique_ptr<AVPacket, av::SmartDeleter> pkt;
+    auto processPkt = inPacket.raw();
     frameFinished = 0;
 
-    AVPacket pkt = *inPacket.raw();
-    pkt.data += offset;
-    pkt.size -= offset;
+    if (inPacket.raw() && offset) {
+        if (offset && inPacket.size() && offset >= inPacket.size())
+            return make_error_pair(Errors::CodecDecodingOffsetToLarge);
+
+        std::error_code ec;
+        pkt.reset(inPacket.makeRef(ec));
+        if (ec) {
+            return {ec.value(), &ec.category()};
+        }
+
+        pkt->data += offset;
+        pkt->size -= offset;
+        processPkt = pkt.get();
+    }
 
-    int decoded = decodeProc(m_raw, outFrame, &frameFinished, &pkt);
-    return make_error_pair(decoded);
+    // not a "flush" internally: just read-out Frame from output queue
+    return make_error_pair(decodeProc(m_raw, outFrame, &frameFinished, processPkt));
 }
 
 std::pair<int, const error_category *> CodecContext2::encodeCommon(Packet &outPacket, const AVFrame *inFrame, int &gotPacket, int (*encodeProc)(AVCodecContext *, AVPacket *, const AVFrame *, int *)) noexcept
@@ -1028,7 +1039,7 @@ CodecContext2::decodeCommon(T &outFrame,
 
     // Dial with PTS/DTS in packet/stream timebase
 
-    if (inPacket.timeBase() != Rational())
+    if (inPacket.raw() && inPacket.timeBase() != Rational())
         outFrame.setTimeBase(inPacket.timeBase());
 #if AVCPP_HAS_AVFORMAT
     else
@@ -1051,7 +1062,7 @@ CodecContext2::decodeCommon(T &outFrame,
     // Convert to decoder/frame time base. Seems not nessesary.
     outFrame.setTimeBase(timeBase());
 
-    if (inPacket)
+    if (inPacket.raw() && inPacket)
         outFrame.setStreamIndex(inPacket.streamIndex());
 #if AVCPP_HAS_AVFORMAT
     else

src/avcpp/packet.cpp

@@ -5,19 +5,25 @@ using namespace std;
 
 namespace av {
 
+#if AVCPP_API_AVCODEC_NEW_INIT_PACKET
+Packet::Packet(std::nullptr_t)
+    : FFWrapperPtr<AVPacket>(nullptr),
+      m_completeFlag(false),
+      m_timeBase(0,0)
+{
+}
+#endif
+
 Packet::Packet()
+    : m_completeFlag(false),
+      m_timeBase(0, 0)
 {
 #if AVCPP_API_AVCODEC_NEW_INIT_PACKET
     m_raw = av_packet_alloc();
 #else
     av_init_packet(raw());
 #endif
-
     raw()->stream_index = -1; // no stream
-
-    m_completeFlag = false;
-    m_timeBase     = Rational(0, 0);
-
 }
 
 Packet::Packet(const Packet &packet)

src/avcpp/packet.h

@@ -65,6 +65,10 @@ class Packet :
      */
     struct wrap_data_static {};
 
+#if AVCPP_API_AVCODEC_NEW_INIT_PACKET
+    explicit Packet(std::nullptr_t); // explicit nullptr packet. There is no extra internal checks, so be careful
+#endif
+
     Packet();
     Packet(const Packet &packet, OptionalErrorCode ec);
     Packet(const Packet &packet);

tests/CMakeLists.txt

@@ -15,7 +15,8 @@ add_executable(test_executor
     PixelSampleFormat.cpp
     Common.cpp
     Buffer.cpp
-    FormatCustomIO_test.cpp)
+    FormatCustomIO_test.cpp
+    CodecContext.cpp)
 target_link_libraries(test_executor PUBLIC Catch2::Catch2WithMain avcpp::avcpp)
 
 list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../catch2/contrib")

tests/CodecContext.cpp

@@ -0,0 +1,67 @@
+//
+//
+// TODO: test incomplete. Sounds like RAWVIDEO decoder does not support multiple frames per-packet: only first one
+//       consumed
+//
+//
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <vector>
+#include <print>
+
+#include "avcpp/avconfig.h"
+#include "avcpp/packet.h"
+#include "avcpp/codeccontext.h"
+
+namespace {
+constexpr std::size_t W = 320;
+constexpr std::size_t H = 240;
+const     av::PixelFormat FMT{AV_PIX_FMT_GRAY8};
+constexpr std::size_t FRAMES = 4;
+constexpr std::size_t FRAME_SIZE = W * H;
+constexpr std::size_t FRAMES_SIZE = FRAME_SIZE * FRAMES;
+}
+
+TEST_CASE("CodecContext")
+{
+    SECTION("Decode packet with multiple frames") {
+
+        std::vector<uint8_t> block;
+        block.reserve(FRAMES_SIZE + AV_INPUT_BUFFER_PADDING_SIZE);
+        block.resize(FRAMES_SIZE); // Gray
+
+        av::Codec vcodec = av::findDecodingCodec(AVCodecID::AV_CODEC_ID_RAWVIDEO);
+        av::VideoDecoderContext vdec{vcodec};
+        vdec.setHeight(H);
+        vdec.setWidth(W);
+        vdec.setPixelFormat(FMT);
+        vdec.setTimeBase({1, 1});
+        vdec.open();
+
+        for (auto i = 0; i < FRAMES; ++i) {
+            std::fill_n(block.data() + i * FRAME_SIZE, FRAME_SIZE, (i + 1) * 50);
+        }
+
+        //
+        av::Packet pkt{block, av::Packet::wrap_data_static{}};
+        pkt.setTimeBase(vdec.timeBase());
+
+        static std::size_t ITERS = 4;
+        std::size_t framesCount = 0;
+        for (auto i = 0; i < ITERS; ++i) {
+            pkt.setPts({i, {1,1}});
+            auto frame = vdec.decode(pkt);
+            if (!frame) // TBD
+                break;
+            // in case, when multiple frames per packet
+            while (frame) {
+                std::println("Frame: {}, cnt={}", int(frame.data()[0]), framesCount++);
+                frame = vdec.decode(av::Packet{nullptr});
+            }
+        }
+
+        // TBD: rawvideo does not support multiple frames per packet.
+        // CHECK(framesCount == ITERS * FRAMES);
+    }
+}

tests/Packet.cpp

@@ -106,6 +106,12 @@ TEST_CASE("Packet define", "[Packet][Construct]")
         CHECK(pkt.refCount() == 1);
     }
 
+    SECTION("Nullptr packet") {
+        av::Packet pkt{nullptr};
+        CHECK(pkt.raw() == nullptr);
+        // any other operation not permitted
+    }
+
     SECTION("setPts/Dts") {
         {
             av::Packet pkt;