Abstract: In one aspect, a method includes receiving from a content-presentation device a request for first supplemental content for presentation during first content-modification operation, and transmitting to the content-presentation device a link to a set of content items in a playlist including the first supplemental content. A request may be received from the content-presentation device for second supplemental content for presentation during a second content-modification operation. A determination may be made that the second content-modification operation is scheduled immediately after the first content-modification operation. Responsive to the determination, the playlist may be modified to include the second supplemental content positioned immediately after the first supplemental content.

Abstract: In one aspect, a method includes receiving, by a content-management system and from a content-presentation device, a request for supplemental content, such as a replacement advertisement. The content-management system may then determine a technical characteristic of the content-presentation device and select supplemental content based at least in part on at least the determined technical characteristic of the content-presentation device. The content-management system may then cause the selected supplemental content to be transmitted to the content-presentation device to facilitate the content-presentation device performing a content modification operation.

Abstract: In one aspect, a method includes receiving first content at a content-presentation device and presenting the first content, the first content comprising a first audio-content component. The content-presentation device may receive second content comprising a second audio-content component. The content-presentation device may determine a switch time at which to switch from presenting the first content to presenting the second content. During a first time interval prior to the switch time and ending at the switch time, the volume of the first audio-content component may be decreased to zero. At the switch time, the content-presentation device may switch from presenting the first content to presenting the second content. During a second time interval beginning at the switch time and ending at a second time after the switch time, the volume of the second audio-content component may be increased from zero to a non-zero volume level.