From 4fc00ce5947427d85a808685d10bde314334ec94 Mon Sep 17 00:00:00 2001
From: David Thorpe <djt@mutablelogic.com>
Date: Mon, 29 Jul 2024 19:37:41 +0200
Subject: [PATCH 1/2] Skip nil frames in decoder

---
 pkg/ffmpeg/decoder.go | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/pkg/ffmpeg/decoder.go b/pkg/ffmpeg/decoder.go
index 40e2bb7..ae8599b 100644
--- a/pkg/ffmpeg/decoder.go
+++ b/pkg/ffmpeg/decoder.go
@@ -155,12 +155,17 @@ func (d *Decoder) decode(packet *ff.AVPacket, fn DecoderFrameFn) error {
 			dest = (*Frame)(d.frame)
 		}
 
+		// If we have a nil frame here, then don't pass back to the caller
+		if dest == nil {
+			ff.AVUtil_frame_unref(d.frame)
+			continue
+		}
+
 		// Copy across the timebase and pts
-		// TODO if dest != nil {
+		// TODO
 		//	fmt.Println("pts=", d.frame.Pts())
-		//		(*ff.AVFrame)(dest).SetPts(d.frame.Pts())
-		//		(*ff.AVFrame)(dest).SetTimeBase(d.timeBase)
-		//}
+		//	(*ff.AVFrame)(dest).SetPts(d.frame.Pts())
+		//	(*ff.AVFrame)(dest).SetTimeBase(d.timeBase)
 
 		// Pass back to the caller
 		if err := fn(d.stream, dest); errors.Is(err, io.EOF) {

From a30a3666ff72023695b9c7878d213859ee13db43 Mon Sep 17 00:00:00 2001
From: David Thorpe <djt@mutablelogic.com>
Date: Mon, 29 Jul 2024 20:32:38 +0200
Subject: [PATCH 2/2] Fixed some resampler issues

---
 pkg/ffmpeg/resampler.go            | 14 +++++++++++++-
 sys/ffmpeg61/avutil_samples.go     | 14 +++++++++++++-
 sys/ffmpeg61/swresample_convert.go | 17 ++++++++---------
 3 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/pkg/ffmpeg/resampler.go b/pkg/ffmpeg/resampler.go
index b88ac47..9beb134 100644
--- a/pkg/ffmpeg/resampler.go
+++ b/pkg/ffmpeg/resampler.go
@@ -128,7 +128,7 @@ func (r *resampler) Frame(src *Frame) (*Frame, error) {
 	}
 
 	// Perform resampling
-	if err := ff.SWResample_convert_frame(r.ctx, (*ff.AVFrame)(src), (*ff.AVFrame)(r.dest)); err != nil {
+	if err := swrConvertFrame(r.ctx, (*ff.AVFrame)(src), (*ff.AVFrame)(r.dest)); err != nil {
 		return nil, fmt.Errorf("SWResample_convert_frame: %w", err)
 	} else if r.dest.NumSamples() == 0 {
 		return nil, nil
@@ -146,6 +146,18 @@ func (r *resampler) Frame(src *Frame) (*Frame, error) {
 ////////////////////////////////////////////////////////////////////////////////
 // PRIVATE METHODS
 
+//func swrConvertFrame_(ctx *ff.SWRContext, src, dest *ff.AVFrame) error {
+//	return ff.SWResample_convert_frame(ctx, src, dest)
+//}
+
+func swrConvertFrame(ctx *ff.SWRContext, src, dest *ff.AVFrame) error {
+	_, err := ff.SWResample_convert(ctx, ff.AVUtil_samples_frame(dest), ff.AVUtil_samples_frame(src))
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
 func newResampler(dest, src *Frame) (*ff.SWRContext, error) {
 	// Create a new resampler
 	ctx := ff.SWResample_alloc()
diff --git a/sys/ffmpeg61/avutil_samples.go b/sys/ffmpeg61/avutil_samples.go
index 26b34b0..cdaa993 100644
--- a/sys/ffmpeg61/avutil_samples.go
+++ b/sys/ffmpeg61/avutil_samples.go
@@ -16,7 +16,7 @@ import (
 import "C"
 
 const (
-	AV_NUM_PLANES = 48
+	AV_NUM_PLANES = 8
 )
 
 type AVSamples struct {
@@ -83,6 +83,18 @@ func (data *AVSamples) NumSamples() int {
 ////////////////////////////////////////////////////////////////////////////////
 // BINDINGS
 
+// Get AVSamples from an AVFrame
+func AVUtil_samples_frame(frame *AVFrame) *AVSamples {
+	return &AVSamples{
+		nb_samples:  frame.nb_samples,
+		nb_channels: frame.channels,
+		sample_fmt:  C.enum_AVSampleFormat(frame.format),
+		plane_size:  frame.linesize[0],
+		buffer_size: frame.linesize[0] * frame.nb_samples,
+		planes:      frame.data,
+	}
+}
+
 // Allocate a samples buffer for nb_samples samples. Return allocated data for each plane, and the stride.
 func AVUtil_samples_alloc(nb_samples, nb_channels int, sample_fmt AVSampleFormat, align bool) (*AVSamples, error) {
 	if nb_channels < 1 {
diff --git a/sys/ffmpeg61/swresample_convert.go b/sys/ffmpeg61/swresample_convert.go
index ee49901..47df74d 100644
--- a/sys/ffmpeg61/swresample_convert.go
+++ b/sys/ffmpeg61/swresample_convert.go
@@ -13,15 +13,14 @@ import "C"
 // PUBLIC METHODS
 
 // Core conversion function. Returns number of samples output per channel.
-// in and in_count can be set to 0 to flush the last few samples out at the end.
-func SWResample_convert(ctx *SWRContext, dst *AVSamples, dst_nb_samples int, src *AVSamples, src_nb_samples int) (int, error) {
-	n := int(C.swr_convert(
-		(*C.struct_SwrContext)(ctx),
-		&dst.planes[0],
-		C.int(dst_nb_samples),
-		&src.planes[0],
-		C.int(src_nb_samples),
-	))
+// src can be set to nil to flush the last few samples out at the end.
+func SWResample_convert(ctx *SWRContext, dest, src *AVSamples) (int, error) {
+	var n int
+	if src != nil {
+		n = int(C.swr_convert((*C.struct_SwrContext)(ctx), &dest.planes[0], dest.nb_samples, &src.planes[0], src.nb_samples))
+	} else {
+		n = int(C.swr_convert((*C.struct_SwrContext)(ctx), &dest.planes[0], dest.nb_samples, nil, 0))
+	}
 	if n < 0 {
 		return 0, AVError(n)
 	} else {