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Fix video encode in MPEG2 "lossless" transcoding

Fixes #11118

It seems that the new video encode API call pipelines the encoding, returning
after each input frame, but not returning a packet the first time around in all
cases.  This change makes it encode the packet, and then keep calling the API
until a packet has actually been encoded (flushing the output).
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Beirdo committed Sep 24, 2012
1 parent 2353ef9 commit 8611c6e6873b21fb53217146a9f790c3721833be
Showing with 23 additions and 18 deletions.
  1. +22 −17 mythtv/programs/mythtranscode/mpeg2fix.cpp
  2. +1 −1 mythtv/programs/mythtranscode/mpeg2fix.h
@@ -1063,7 +1063,7 @@ extern "C" {
#include "helper.h"
int MPEG2fixup::BuildFrame(AVPacket *pkt, QString fname)
bool MPEG2fixup::BuildFrame(AVPacket *pkt, QString fname)
const mpeg2_info_t *info;
int outbuf_size;
@@ -1074,7 +1074,7 @@ int MPEG2fixup::BuildFrame(AVPacket *pkt, QString fname)
info = mpeg2_info(img_decoder);
if (!info->display_fbuf)
return 1;
return true;
outbuf_size = info->sequence->width * info->sequence->height * 2;
@@ -1116,16 +1116,11 @@ int MPEG2fixup::BuildFrame(AVPacket *pkt, QString fname)
LOG(VB_GENERAL, LOG_ERR, "Couldn't find MPEG2 encoder");
return 1;
return true;
c = avcodec_alloc_context3(NULL);
//We disable all optimizations for the time being. There shouldn't be too
//much encoding going on, and the optimizations have been shown to cause
//corruption in some cases
c->dsp_mask = 0xffff;
//NOTE: The following may seem wrong, but avcodec requires
//sequence->progressive == frame->progressive
//We fix the discrepancy by discarding avcodec's sequence header, and
@@ -1164,19 +1159,29 @@ int MPEG2fixup::BuildFrame(AVPacket *pkt, QString fname)
LOG(VB_GENERAL, LOG_ERR, "could not open codec");
return 1;
return true;
int got_packet = 0;
int ret;
bool initial = true;
int ret = avcodec_encode_video2(c, pkt, picture, &got_packet);
if (ret < 0 || !got_packet)
// Need to call this repeatedly as it seems to be pipelined. The first
// call will return no packet, then the second one will flush it. In case
// it becomes more pipelined, just loop until it creates a packet or errors
// out.
while (!got_packet)
QString("avcodec_encode_video failed (%1)").arg(pkt->size));
return 1;
ret = avcodec_encode_video2(c, pkt, (initial ? picture : NULL),
if (ret < 0)
QString("avcodec_encode_video2 failed (%1)").arg(ret));
return true;
if (!fname.isEmpty())
@@ -1198,7 +1203,7 @@ int MPEG2fixup::BuildFrame(AVPacket *pkt, QString fname)
return 0;
return false;
#define MAX_FRAMES 20000
@@ -171,7 +171,7 @@ class MPEG2fixup
void WriteFrame(QString filename, AVPacket *pkt);
void WriteYUV(QString filename, const mpeg2_info_t *info);
void WriteData(QString filename, uint8_t *data, int size);
int BuildFrame(AVPacket *pkt, QString fname);
bool BuildFrame(AVPacket *pkt, QString fname);
MPEG2frame *GetPoolFrame(AVPacket *pkt);
MPEG2frame *GetPoolFrame(MPEG2frame *f);
int GetFrame(AVPacket *pkt);

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