diff --git a/libavcodec/gifdec.c b/libavcodec/gifdec.c
index e5e84aea12..b0254decd1 100644
--- a/libavcodec/gifdec.c
+++ b/libavcodec/gifdec.c
@@ -410,10 +410,11 @@ static int gif_read_header1(GifState *s)
 
 static int gif_parse_next_image(GifState *s, int *got_picture)
 {
-    int ret;
+
     *got_picture = 1;
     while (bytestream2_get_bytes_left(&s->gb)) {
         int code = bytestream2_get_byte(&s->gb);
+        int ret;
 
         av_dlog(s->avctx, "code=%02x '%c'\n", code, code);
 
diff --git a/libavcodec/interplayvideo.c b/libavcodec/interplayvideo.c
index f1a2a3856a..3285578a70 100644
--- a/libavcodec/interplayvideo.c
+++ b/libavcodec/interplayvideo.c
@@ -74,11 +74,11 @@ static int copy_from(IpvideoContext *s, AVFrame *src, int delta_x, int delta_y)
                        + delta_x * (1 + s->is_16bpp);
     if (motion_offset < 0) {
         av_log(s->avctx, AV_LOG_ERROR, "motion offset < 0 (%d)\n", motion_offset);
-        return -1;
+        return AVERROR_INVALIDDATA;
     } else if (motion_offset > s->upper_motion_limit_offset) {
         av_log(s->avctx, AV_LOG_ERROR, "motion offset above limit (%d >= %d)\n",
             motion_offset, s->upper_motion_limit_offset);
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
     if (src->data[0] == NULL) {
         av_log(s->avctx, AV_LOG_ERROR, "Invalid decode type, corrupted header?\n");
@@ -882,12 +882,8 @@ static void ipvideo_decode_opcodes(IpvideoContext *s)
     int x, y;
     unsigned char opcode;
     int ret;
-    static int frame = 0;
     GetBitContext gb;
 
-    av_dlog(s->avctx, "frame %d\n", frame);
-    frame++;
-
     bytestream2_skip(&s->stream_ptr, 14); /* data starts 14 bytes in */
     if (!s->is_16bpp) {
         /* this is PAL8, so make the palette available */
@@ -923,7 +919,7 @@ static void ipvideo_decode_opcodes(IpvideoContext *s)
             }
             if (ret != 0) {
                 av_log(s->avctx, AV_LOG_ERROR, "decode problem on frame %d, @ block (%d, %d)\n",
-                       frame, x, y);
+                       s->avctx->frame_number, x, y);
                 return;
             }
         }
@@ -963,6 +959,7 @@ static int ipvideo_decode_frame(AVCodecContext *avctx,
     const uint8_t *buf = avpkt->data;
     int buf_size = avpkt->size;
     IpvideoContext *s = avctx->priv_data;
+    int ret;
 
     /* decoding map contains 4 bits of information per 8x8 block */
     s->decoding_map_size = avctx->width * avctx->height / (8 * 8 * 2);
@@ -977,9 +974,9 @@ static int ipvideo_decode_frame(AVCodecContext *avctx,
                      buf_size - s->decoding_map_size);
 
     s->current_frame.reference = 3;
-    if (ff_get_buffer(avctx, &s->current_frame)) {
+    if ((ret = ff_get_buffer(avctx, &s->current_frame)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-        return -1;
+        return ret;
     }
 
     if (!s->is_16bpp) {
diff --git a/libavcodec/lcldec.c b/libavcodec/lcldec.c
index 5708a12d3d..159e0a1401 100644
--- a/libavcodec/lcldec.c
+++ b/libavcodec/lcldec.c
@@ -138,7 +138,7 @@ static int zlib_decomp(AVCodecContext *avctx, const uint8_t *src, int src_len, i
     int zret = inflateReset(&c->zstream);
     if (zret != Z_OK) {
         av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", zret);
-        return -1;
+        return AVERROR_UNKNOWN;
     }
     c->zstream.next_in = (uint8_t *)src;
     c->zstream.avail_in = src_len;
@@ -147,12 +147,12 @@ static int zlib_decomp(AVCodecContext *avctx, const uint8_t *src, int src_len, i
     zret = inflate(&c->zstream, Z_FINISH);
     if (zret != Z_OK && zret != Z_STREAM_END) {
         av_log(avctx, AV_LOG_ERROR, "Inflate error: %d\n", zret);
-        return -1;
+        return AVERROR_UNKNOWN;
     }
     if (expected != (unsigned int)c->zstream.total_out) {
         av_log(avctx, AV_LOG_ERROR, "Decoded size differs (%d != %lu)\n",
                expected, c->zstream.total_out);
-        return -1;
+        return AVERROR_UNKNOWN;
     }
     return c->zstream.total_out;
 }
@@ -178,7 +178,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
     unsigned int height = avctx->height; // Real image height
     unsigned int mszh_dlen;
     unsigned char yq, y1q, uq, vq;
-    int uqvq;
+    int uqvq, ret;
     unsigned int mthread_inlen, mthread_outlen;
     unsigned int len = buf_size;
 
@@ -187,9 +187,9 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
 
     c->pic.reference = 0;
     c->pic.buffer_hints = FF_BUFFER_HINTS_VALID;
-    if(ff_get_buffer(avctx, &c->pic) < 0){
+    if ((ret = ff_get_buffer(avctx, &c->pic)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-        return -1;
+        return ret;
     }
 
     outptr = c->pic.data[0]; // Output image pointer
@@ -210,14 +210,14 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
                 if (mthread_outlen != mszh_dlen) {
                     av_log(avctx, AV_LOG_ERROR, "Mthread1 decoded size differs (%d != %d)\n",
                            mthread_outlen, mszh_dlen);
-                    return -1;
+                    return AVERROR_INVALIDDATA;
                 }
                 mszh_dlen = mszh_decomp(encoded + 8 + mthread_inlen, len - 8 - mthread_inlen,
                                         c->decomp_buf + mthread_outlen, c->decomp_size - mthread_outlen);
                 if (mthread_outlen != mszh_dlen) {
                     av_log(avctx, AV_LOG_ERROR, "Mthread2 decoded size differs (%d != %d)\n",
                            mthread_outlen, mszh_dlen);
-                    return -1;
+                    return AVERROR_INVALIDDATA;
                 }
                 encoded = c->decomp_buf;
                 len = c->decomp_size;
@@ -226,7 +226,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
                 if (c->decomp_size != mszh_dlen) {
                     av_log(avctx, AV_LOG_ERROR, "Decoded size differs (%d != %d)\n",
                            c->decomp_size, mszh_dlen);
-                    return -1;
+                    return AVERROR_INVALIDDATA;
                 }
                 encoded = c->decomp_buf;
                 len = mszh_dlen;
@@ -257,7 +257,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
         }
         default:
             av_log(avctx, AV_LOG_ERROR, "BUG! Unknown MSZH compression in frame decoder.\n");
-            return -1;
+            return AVERROR_INVALIDDATA;
         }
         break;
 #if CONFIG_ZLIB_DECODER
@@ -274,7 +274,6 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
                 break;
             }
         } else if (c->flags & FLAG_MULTITHREAD) {
-            int ret;
             mthread_inlen = AV_RL32(encoded);
             mthread_inlen = FFMIN(mthread_inlen, len - 8);
             mthread_outlen = AV_RL32(encoded+4);
@@ -294,7 +293,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
 #endif
     default:
         av_log(avctx, AV_LOG_ERROR, "BUG! Unknown codec in frame decoder compression switch.\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
 
@@ -378,7 +377,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
             break;
         default:
             av_log(avctx, AV_LOG_ERROR, "BUG! Unknown imagetype in pngfilter switch.\n");
-            return -1;
+            return AVERROR_INVALIDDATA;
         }
     }
 
@@ -466,7 +465,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "BUG! Unknown imagetype in image decoder.\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     *got_frame = 1;
diff --git a/libavcodec/nuv.c b/libavcodec/nuv.c
index ff11d007c4..10dce6a549 100644
--- a/libavcodec/nuv.c
+++ b/libavcodec/nuv.c
@@ -88,7 +88,7 @@ static int get_quant(AVCodecContext *avctx, NuvContext *c, const uint8_t *buf,
     int i;
     if (size < 2 * 64 * 4) {
         av_log(avctx, AV_LOG_ERROR, "insufficient rtjpeg quant data\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
     for (i = 0; i < 64; i++, buf += 4)
         c->lq[i] = AV_RL32(buf);
@@ -114,6 +114,8 @@ static int codec_reinit(AVCodecContext *avctx, int width, int height,
                         int quality)
 {
     NuvContext *c = avctx->priv_data;
+    int ret;
+
     width  = FFALIGN(width,  2);
     height = FFALIGN(height, 2);
     if (quality >= 0)
@@ -121,9 +123,10 @@ static int codec_reinit(AVCodecContext *avctx, int width, int height,
     if (width != c->width || height != c->height) {
         // also reserve space for a possible additional header
         int buf_size = 24 + height * width * 3 / 2 + AV_LZO_OUTPUT_PADDING;
-        if (av_image_check_size(height, width, 0, avctx) < 0 ||
-            buf_size > INT_MAX/8)
+        if (buf_size > INT_MAX/8)
             return -1;
+        if ((ret = av_image_check_size(height, width, 0, avctx)) < 0)
+            return ret;
         avctx->width  = c->width  = width;
         avctx->height = c->height = height;
         av_fast_malloc(&c->decomp_buf, &c->decomp_size,
@@ -165,7 +168,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
 
     if (buf_size < 12) {
         av_log(avctx, AV_LOG_ERROR, "coded frame too small\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     // codec data (rtjpeg quant tables)
@@ -184,7 +187,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
 
     if (buf_size < 12 || buf[0] != 'V') {
         av_log(avctx, AV_LOG_ERROR, "not a nuv video frame\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
     comptype = buf[1];
     switch (comptype) {
@@ -227,16 +230,15 @@ retry:
         w = AV_RL16(&buf[6]);
         h = AV_RL16(&buf[8]);
         q = buf[10];
-        res = codec_reinit(avctx, w, h, q);
-        if (res < 0)
-            return res;
-        if (res) {
+        if ((result = codec_reinit(avctx, w, h, q)) < 0)
+            return result;
+        if (result) {
             buf = avpkt->data;
             buf_size = avpkt->size;
             size_change = 1;
             goto retry;
         }
-        buf = &buf[RTJPEG_HEADER_SIZE];
+        buf       = &buf[RTJPEG_HEADER_SIZE];
         buf_size -= RTJPEG_HEADER_SIZE;
     }
 
@@ -248,7 +250,7 @@ retry:
     result = avctx->reget_buffer(avctx, &c->pic);
     if (result < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-        return -1;
+        return result;
     }
 
     c->pic.pict_type = keyframe ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
@@ -280,7 +282,7 @@ retry:
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "unknown compression\n");
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
 
     *picture   = c->pic;
@@ -291,6 +293,8 @@ retry:
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     NuvContext *c  = avctx->priv_data;
+    int ret;
+
     avctx->pix_fmt = AV_PIX_FMT_YUV420P;
     c->pic.data[0] = NULL;
     c->decomp_buf  = NULL;
@@ -305,8 +309,8 @@ static av_cold int decode_init(AVCodecContext *avctx)
 
     ff_dsputil_init(&c->dsp, avctx);
 
-    if (codec_reinit(avctx, avctx->width, avctx->height, -1) < 0)
-        return 1;
+    if ((ret = codec_reinit(avctx, avctx->width, avctx->height, -1)) < 0)
+        return ret;
 
     return 0;
 }
diff --git a/libavcodec/qdrw.c b/libavcodec/qdrw.c
index 2be6e04b64..71fe48aea6 100644
--- a/libavcodec/qdrw.c
+++ b/libavcodec/qdrw.c
@@ -45,7 +45,7 @@ static int decode_frame(AVCodecContext *avctx,
     AVFrame * const p = &a->pic;
     uint8_t* outdata;
     int colors;
-    int i;
+    int i, ret;
     uint32_t *pal;
     int r, g, b;
 
@@ -53,9 +53,9 @@ static int decode_frame(AVCodecContext *avctx,
         avctx->release_buffer(avctx, p);
 
     p->reference= 0;
-    if(ff_get_buffer(avctx, p) < 0){
+    if ((ret = ff_get_buffer(avctx, p)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-        return -1;
+        return ret;
     }
     p->pict_type= AV_PICTURE_TYPE_I;
     p->key_frame= 1;
@@ -70,7 +70,7 @@ static int decode_frame(AVCodecContext *avctx,
 
     if(colors < 0 || colors > 256) {
         av_log(avctx, AV_LOG_ERROR, "Error color count - %i(0x%X)\n", colors, colors);
-        return -1;
+        return AVERROR_INVALIDDATA;
     }
     if (buf_end - buf < (colors + 1) * 8)
         return AVERROR_INVALIDDATA;
diff --git a/libavcodec/qpeg.c b/libavcodec/qpeg.c
index 105ac69600..73d652e5d8 100644
--- a/libavcodec/qpeg.c
+++ b/libavcodec/qpeg.c
@@ -258,7 +258,7 @@ static int decode_frame(AVCodecContext *avctx,
     AVFrame *  p = &a->pic;
     AVFrame * ref= &a->ref;
     uint8_t* outdata;
-    int delta;
+    int delta, ret;
     const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);
 
     if (avpkt->size < 0x86) {
@@ -273,9 +273,9 @@ static int decode_frame(AVCodecContext *avctx,
     FFSWAP(AVFrame, *ref, *p);
 
     p->reference= 3;
-    if(ff_get_buffer(avctx, p) < 0){
+    if ((ret = ff_get_buffer(avctx, p)) < 0) {
         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
-        return -1;
+        return ret;
     }
     outdata = a->pic.data[0];
     bytestream2_skip(&a->buffer, 4);
diff --git a/libavcodec/qtrle.c b/libavcodec/qtrle.c
index 41fda4b3b6..5acd2eb3ae 100644
--- a/libavcodec/qtrle.c
+++ b/libavcodec/qtrle.c
@@ -407,14 +407,15 @@ static int qtrle_decode_frame(AVCodecContext *avctx,
     int header, start_line;
     int height, row_ptr;
     int has_palette = 0;
+    int ret;
 
     bytestream2_init(&s->g, avpkt->data, avpkt->size);
     s->frame.reference = 3;
     s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE |
                             FF_BUFFER_HINTS_REUSABLE | FF_BUFFER_HINTS_READABLE;
-    if (avctx->reget_buffer(avctx, &s->frame)) {
+    if ((ret = avctx->reget_buffer(avctx, &s->frame)) < 0) {
         av_log (s->avctx, AV_LOG_ERROR, "reget_buffer() failed\n");
-        return -1;
+        return ret;
     }
 
     /* check if this frame is even supposed to change */
diff --git a/libavcodec/targa.c b/libavcodec/targa.c
index 18ad21d036..11a8f213fd 100644
--- a/libavcodec/targa.c
+++ b/libavcodec/targa.c
@@ -178,7 +178,7 @@ static int decode_frame(AVCodecContext *avctx,
         return AVERROR_INVALIDDATA;
     }
 
-    if ((ret = av_image_check_size(w, h, 0, avctx)))
+    if ((ret = av_image_check_size(w, h, 0, avctx)) < 0)
         return ret;
     if (w != avctx->width || h != avctx->height)
         avcodec_set_dimensions(avctx, w, h);
@@ -200,6 +200,7 @@ static int decode_frame(AVCodecContext *avctx,
 
     if (colors) {
         int pal_size, pal_sample_size;
+
         switch (csize) {
         case 32: pal_sample_size = 4; break;
         case 24: pal_sample_size = 3; break;