Bandwidth efficiency and error robustness are two essential and conflicting requirements for streaming media content over error-prone channels, such as wireless channels. This paper describes a new scheme called content-based unequal error protection (C-UEP), which aims to improve the user-perceived QoS in the case of packet loss. We use music streaming as an example to show the effectiveness of the new concept. C-UEP requires only a small fraction of the redundancy used in existing forward error correction (FEC) methods. C-UEP classifies every audio segment (e.g. an encoding frame) into different classes to improve encoding efficiency. Salient transients such as drumbeats and note onsets are encoded with more redundancy in a secondary bitstream used to recover lost packets by the receiver. Formal perceptual evaluations show that our scheme improves audio quality significantly over simple muting and packet repetition baselines. This improvement is achieved with a negligible amount of redundancy, which is transmitted to the receiver ahead of playback.