[FFmpeg-devel] [RFC/PATCH]Interlaced lossless

[Carl Eugen Hoyos]

Hi!

Attached patch fixes ticket #2190 for me (if using mov which supports saving 
interlace information like yuv4mpeg).
It duplicates some code across decoders, this may indicate that it is not 
entirely correct - please advise!

If ok, I will split as requested.

Please review, Carl Eugen
-------------- next part --------------
diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index a1da544..31674ca 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -724,6 +724,13 @@ static av_cold int decode_init(AVCodecContext *avctx)
     if ((ret = ffv1_init_slice_contexts(f)) < 0)
         return ret;
 
+    if (avctx->field_order > AV_FIELD_PROGRESSIVE) { /*we have interlaced material flagged in container */
+        AVFrame *p    = &f->picture;
+        p->interlaced_frame = 1;
+        if (avctx->field_order == AV_FIELD_TT || avctx->field_order == AV_FIELD_TB)
+            p->top_field_first = 1;
+    }
+
     return 0;
 }
 
diff --git a/libavcodec/huffyuvdec.c b/libavcodec/huffyuvdec.c
index 9c92bf3..cba8100 100644
--- a/libavcodec/huffyuvdec.c
+++ b/libavcodec/huffyuvdec.c
@@ -344,6 +344,13 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return AVERROR(ENOMEM);
     }
 
+    if (avctx->field_order > AV_FIELD_PROGRESSIVE) { /*we have interlaced material flagged in container */
+        AVFrame *p    = &s->picture;
+        p->interlaced_frame = 1;
+        if (avctx->field_order == AV_FIELD_TT || avctx->field_order == AV_FIELD_TB)
+            p->top_field_first = 1;
+    }
+
     return 0;
 }
 
diff --git a/libavformat/yuv4mpeg.c b/libavformat/yuv4mpeg.c
index ff039bd..272a104 100644
--- a/libavformat/yuv4mpeg.c
+++ b/libavformat/yuv4mpeg.c
@@ -56,8 +56,8 @@ static int yuv4_generate_header(AVFormatContext *s, char* buf)
         aspectd = 0;  // 0:0 means unknown
 
     inter = 'p'; /* progressive is the default */
-    if (st->codec->coded_frame && st->codec->coded_frame->interlaced_frame)
-        inter = st->codec->coded_frame->top_field_first ? 't' : 'b';
+    if (st->codec->field_order > AV_FIELD_PROGRESSIVE)
+        inter = st->codec->field_order == AV_FIELD_TT || st->codec->field_order == AV_FIELD_TB ? 't' : 'b';
 
     switch (st->codec->pix_fmt) {
     case AV_PIX_FMT_GRAY8:
@@ -319,7 +319,7 @@ static int yuv4_read_header(AVFormatContext *s)
 {
     char header[MAX_YUV4_HEADER + 10];  // Include headroom for
                                         // the longest option
-    char *tokstart, *tokend, *header_end;
+    char *tokstart, *tokend, *header_end, interlaced = '?';
     int i;
     AVIOContext *pb = s->pb;
     int width = -1, height  = -1, raten   = 0,
@@ -425,28 +425,7 @@ static int yuv4_read_header(AVFormatContext *s)
                 tokstart++;
             break;
         case 'I': // Interlace type
-            switch (*tokstart++){
-            case '?':
-                break;
-            case 'p':
-                s1->interlaced_frame = 0;
-                break;
-            case 't':
-                s1->interlaced_frame = 1;
-                s1->top_field_first = 1;
-                break;
-            case 'b':
-                s1->interlaced_frame = 1;
-                s1->top_field_first = 0;
-                break;
-            case 'm':
-                av_log(s, AV_LOG_ERROR, "YUV4MPEG stream contains mixed "
-                       "interlaced and non-interlaced frames.\n");
-                return -1;
-            default:
-                av_log(s, AV_LOG_ERROR, "YUV4MPEG has invalid header.\n");
-                return -1;
-            }
+            interlaced = *tokstart++;
             break;
         case 'F': // Frame rate
             sscanf(tokstart, "%d:%d", &raten, &rated); // 0:0 if unknown
@@ -547,6 +526,27 @@ static int yuv4_read_header(AVFormatContext *s)
     st->sample_aspect_ratio           = (AVRational){ aspectn, aspectd };
     st->codec->chroma_sample_location = chroma_sample_location;
 
+    switch (interlaced){
+    case 'p':
+        st->codec->field_order = AV_FIELD_PROGRESSIVE;
+        break;
+    case 't':
+        st->codec->field_order = AV_FIELD_TT;
+        break;
+    case 'b':
+        st->codec->field_order = AV_FIELD_BB;
+        break;
+    case 'm':
+        av_log(s, AV_LOG_ERROR, "YUV4MPEG stream contains mixed "
+               "interlaced and non-interlaced frames.\n");
+    case '?':
+        st->codec->field_order = AV_FIELD_UNKNOWN;
+        break;
+    default:
+        av_log(s, AV_LOG_ERROR, "YUV4MPEG has invalid header.\n");
+        st->codec->field_order = AV_FIELD_UNKNOWN;
+    }
+
     return 0;
 }
 
@@ -556,7 +556,6 @@ static int yuv4_read_packet(AVFormatContext *s, AVPacket *pkt)
     char header[MAX_FRAME_HEADER+1];
     int packet_size, width, height, ret;
     AVStream *st = s->streams[0];
-    struct frame_attributes *s1 = s->priv_data;
 
     for (i = 0; i < MAX_FRAME_HEADER; i++) {
         header[i] = avio_r8(s->pb);
@@ -588,11 +587,6 @@ static int yuv4_read_packet(AVFormatContext *s, AVPacket *pkt)
     else if (ret != packet_size)
         return s->pb->eof_reached ? AVERROR_EOF : AVERROR(EIO);
 
-    if (st->codec->coded_frame) {
-        st->codec->coded_frame->interlaced_frame = s1->interlaced_frame;
-        st->codec->coded_frame->top_field_first  = s1->top_field_first;
-    }
-
     pkt->stream_index = 0;
     return 0;
 }